folio->mapping = NULL; /* Leave folio->index set: truncation lookup relies upon it */
mapping->nrpages -= nr;
}
staticvoid filemap_unaccount_folio(struct address_space *mapping, struct folio *folio)
{ long nr;
VM_BUG_ON_FOLIO(folio_mapped(folio), folio); if (!IS_ENABLED(CONFIG_DEBUG_VM) && unlikely(folio_mapped(folio))) {
pr_alert("BUG: Bad page cache in process %s pfn:%05lx\n",
current->comm, folio_pfn(folio));
dump_page(&folio->page, "still mapped when deleted");
dump_stack();
add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
if (mapping_exiting(mapping) && !folio_test_large(folio)) { int mapcount = folio_mapcount(folio);
if (folio_ref_count(folio) >= mapcount + 2) { /* * All vmas have already been torn down, so it's * a good bet that actually the page is unmapped * and we'd rather not leak it: if we're wrong, * another bad page check should catch it later.
*/
atomic_set(&folio->_mapcount, -1);
folio_ref_sub(folio, mapcount);
}
}
}
/* hugetlb folios do not participate in page cache accounting. */ if (folio_test_hugetlb(folio)) return;
/* * At this point folio must be either written or cleaned by * truncate. Dirty folio here signals a bug and loss of * unwritten data - on ordinary filesystems. * * But it's harmless on in-memory filesystems like tmpfs; and can * occur when a driver which did get_user_pages() sets page dirty * before putting it, while the inode is being finally evicted. * * Below fixes dirty accounting after removing the folio entirely * but leaves the dirty flag set: it has no effect for truncated * folio and anyway will be cleared before returning folio to * buddy allocator.
*/ if (WARN_ON_ONCE(folio_test_dirty(folio) &&
mapping_can_writeback(mapping)))
folio_account_cleaned(folio, inode_to_wb(mapping->host));
}
/* * Delete a page from the page cache and free it. Caller has to make * sure the page is locked and that nobody else uses it - or that usage * is safe. The caller must hold the i_pages lock.
*/ void __filemap_remove_folio(struct folio *folio, void *shadow)
{ struct address_space *mapping = folio->mapping;
free_folio = mapping->a_ops->free_folio; if (free_folio)
free_folio(folio);
folio_put_refs(folio, folio_nr_pages(folio));
}
/** * filemap_remove_folio - Remove folio from page cache. * @folio: The folio. * * This must be called only on folios that are locked and have been * verified to be in the page cache. It will never put the folio into * the free list because the caller has a reference on the page.
*/ void filemap_remove_folio(struct folio *folio)
{ struct address_space *mapping = folio->mapping;
BUG_ON(!folio_test_locked(folio));
spin_lock(&mapping->host->i_lock);
xa_lock_irq(&mapping->i_pages);
__filemap_remove_folio(folio, NULL);
xa_unlock_irq(&mapping->i_pages); if (mapping_shrinkable(mapping))
inode_add_lru(mapping->host);
spin_unlock(&mapping->host->i_lock);
filemap_free_folio(mapping, folio);
}
/* * page_cache_delete_batch - delete several folios from page cache * @mapping: the mapping to which folios belong * @fbatch: batch of folios to delete * * The function walks over mapping->i_pages and removes folios passed in * @fbatch from the mapping. The function expects @fbatch to be sorted * by page index and is optimised for it to be dense. * It tolerates holes in @fbatch (mapping entries at those indices are not * modified). * * The function expects the i_pages lock to be held.
*/ staticvoid page_cache_delete_batch(struct address_space *mapping, struct folio_batch *fbatch)
{
XA_STATE(xas, &mapping->i_pages, fbatch->folios[0]->index); long total_pages = 0; int i = 0; struct folio *folio;
mapping_set_update(&xas, mapping);
xas_for_each(&xas, folio, ULONG_MAX) { if (i >= folio_batch_count(fbatch)) break;
/* A swap/dax/shadow entry got inserted? Skip it. */ if (xa_is_value(folio)) continue; /* * A page got inserted in our range? Skip it. We have our * pages locked so they are protected from being removed. * If we see a page whose index is higher than ours, it * means our page has been removed, which shouldn't be * possible because we're holding the PageLock.
*/ if (folio != fbatch->folios[i]) {
VM_BUG_ON_FOLIO(folio->index >
fbatch->folios[i]->index, folio); continue;
}
WARN_ON_ONCE(!folio_test_locked(folio));
folio->mapping = NULL; /* Leave folio->index set: truncation lookup relies on it */
for (i = 0; i < folio_batch_count(fbatch); i++)
filemap_free_folio(mapping, fbatch->folios[i]);
}
int filemap_check_errors(struct address_space *mapping)
{ int ret = 0; /* Check for outstanding write errors */ if (test_bit(AS_ENOSPC, &mapping->flags) &&
test_and_clear_bit(AS_ENOSPC, &mapping->flags))
ret = -ENOSPC; if (test_bit(AS_EIO, &mapping->flags) &&
test_and_clear_bit(AS_EIO, &mapping->flags))
ret = -EIO; return ret;
}
EXPORT_SYMBOL(filemap_check_errors);
staticint filemap_check_and_keep_errors(struct address_space *mapping)
{ /* Check for outstanding write errors */ if (test_bit(AS_EIO, &mapping->flags)) return -EIO; if (test_bit(AS_ENOSPC, &mapping->flags)) return -ENOSPC; return 0;
}
/** * filemap_fdatawrite_wbc - start writeback on mapping dirty pages in range * @mapping: address space structure to write * @wbc: the writeback_control controlling the writeout * * Call writepages on the mapping using the provided wbc to control the * writeout. * * Return: %0 on success, negative error code otherwise.
*/ int filemap_fdatawrite_wbc(struct address_space *mapping, struct writeback_control *wbc)
{ int ret;
if (!mapping_can_writeback(mapping) ||
!mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) return 0;
/** * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range * @mapping: address space structure to write * @start: offset in bytes where the range starts * @end: offset in bytes where the range ends (inclusive) * @sync_mode: enable synchronous operation * * Start writeback against all of a mapping's dirty pages that lie * within the byte offsets <start, end> inclusive. * * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as * opposed to a regular memory cleansing writeback. The difference between * these two operations is that if a dirty page/buffer is encountered, it must * be waited upon, and not just skipped over. * * Return: %0 on success, negative error code otherwise.
*/ int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
loff_t end, int sync_mode)
{ struct writeback_control wbc = {
.sync_mode = sync_mode,
.nr_to_write = LONG_MAX,
.range_start = start,
.range_end = end,
};
/** * filemap_fdatawrite_range_kick - start writeback on a range * @mapping: target address_space * @start: index to start writeback on * @end: last (inclusive) index for writeback * * This is a non-integrity writeback helper, to start writing back folios * for the indicated range. * * Return: %0 on success, negative error code otherwise.
*/ int filemap_fdatawrite_range_kick(struct address_space *mapping, loff_t start,
loff_t end)
{ return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_NONE);
}
EXPORT_SYMBOL_GPL(filemap_fdatawrite_range_kick);
/** * filemap_flush - mostly a non-blocking flush * @mapping: target address_space * * This is a mostly non-blocking flush. Not suitable for data-integrity * purposes - I/O may not be started against all dirty pages. * * Return: %0 on success, negative error code otherwise.
*/ int filemap_flush(struct address_space *mapping)
{ return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
}
EXPORT_SYMBOL(filemap_flush);
/** * filemap_range_has_page - check if a page exists in range. * @mapping: address space within which to check * @start_byte: offset in bytes where the range starts * @end_byte: offset in bytes where the range ends (inclusive) * * Find at least one page in the range supplied, usually used to check if * direct writing in this range will trigger a writeback. * * Return: %true if at least one page exists in the specified range, * %false otherwise.
*/ bool filemap_range_has_page(struct address_space *mapping,
loff_t start_byte, loff_t end_byte)
{ struct folio *folio;
XA_STATE(xas, &mapping->i_pages, start_byte >> PAGE_SHIFT);
pgoff_t max = end_byte >> PAGE_SHIFT;
if (end_byte < start_byte) returnfalse;
rcu_read_lock(); for (;;) {
folio = xas_find(&xas, max); if (xas_retry(&xas, folio)) continue; /* Shadow entries don't count */ if (xa_is_value(folio)) continue; /* * We don't need to try to pin this page; we're about to * release the RCU lock anyway. It is enough to know that * there was a page here recently.
*/ break;
}
rcu_read_unlock();
/** * filemap_fdatawait_range - wait for writeback to complete * @mapping: address space structure to wait for * @start_byte: offset in bytes where the range starts * @end_byte: offset in bytes where the range ends (inclusive) * * Walk the list of under-writeback pages of the given address space * in the given range and wait for all of them. Check error status of * the address space and return it. * * Since the error status of the address space is cleared by this function, * callers are responsible for checking the return value and handling and/or * reporting the error. * * Return: error status of the address space.
*/ int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte,
loff_t end_byte)
{
__filemap_fdatawait_range(mapping, start_byte, end_byte); return filemap_check_errors(mapping);
}
EXPORT_SYMBOL(filemap_fdatawait_range);
/** * filemap_fdatawait_range_keep_errors - wait for writeback to complete * @mapping: address space structure to wait for * @start_byte: offset in bytes where the range starts * @end_byte: offset in bytes where the range ends (inclusive) * * Walk the list of under-writeback pages of the given address space in the * given range and wait for all of them. Unlike filemap_fdatawait_range(), * this function does not clear error status of the address space. * * Use this function if callers don't handle errors themselves. Expected * call sites are system-wide / filesystem-wide data flushers: e.g. sync(2), * fsfreeze(8)
*/ int filemap_fdatawait_range_keep_errors(struct address_space *mapping,
loff_t start_byte, loff_t end_byte)
{
__filemap_fdatawait_range(mapping, start_byte, end_byte); return filemap_check_and_keep_errors(mapping);
}
EXPORT_SYMBOL(filemap_fdatawait_range_keep_errors);
/** * file_fdatawait_range - wait for writeback to complete * @file: file pointing to address space structure to wait for * @start_byte: offset in bytes where the range starts * @end_byte: offset in bytes where the range ends (inclusive) * * Walk the list of under-writeback pages of the address space that file * refers to, in the given range and wait for all of them. Check error * status of the address space vs. the file->f_wb_err cursor and return it. * * Since the error status of the file is advanced by this function, * callers are responsible for checking the return value and handling and/or * reporting the error. * * Return: error status of the address space vs. the file->f_wb_err cursor.
*/ int file_fdatawait_range(struct file *file, loff_t start_byte, loff_t end_byte)
{ struct address_space *mapping = file->f_mapping;
/** * filemap_fdatawait_keep_errors - wait for writeback without clearing errors * @mapping: address space structure to wait for * * Walk the list of under-writeback pages of the given address space * and wait for all of them. Unlike filemap_fdatawait(), this function * does not clear error status of the address space. * * Use this function if callers don't handle errors themselves. Expected * call sites are system-wide / filesystem-wide data flushers: e.g. sync(2), * fsfreeze(8) * * Return: error status of the address space.
*/ int filemap_fdatawait_keep_errors(struct address_space *mapping)
{
__filemap_fdatawait_range(mapping, 0, LLONG_MAX); return filemap_check_and_keep_errors(mapping);
}
EXPORT_SYMBOL(filemap_fdatawait_keep_errors);
/* Returns true if writeback might be needed or already in progress. */ staticbool mapping_needs_writeback(struct address_space *mapping)
{ return mapping->nrpages;
}
rcu_read_lock();
xas_for_each(&xas, folio, max) { if (xas_retry(&xas, folio)) continue; if (xa_is_value(folio)) continue; if (folio_test_dirty(folio) || folio_test_locked(folio) ||
folio_test_writeback(folio)) break;
}
rcu_read_unlock(); return folio != NULL;
}
EXPORT_SYMBOL_GPL(filemap_range_has_writeback);
/** * filemap_write_and_wait_range - write out & wait on a file range * @mapping: the address_space for the pages * @lstart: offset in bytes where the range starts * @lend: offset in bytes where the range ends (inclusive) * * Write out and wait upon file offsets lstart->lend, inclusive. * * Note that @lend is inclusive (describes the last byte to be written) so * that this function can be used to write to the very end-of-file (end = -1). * * Return: error status of the address space.
*/ int filemap_write_and_wait_range(struct address_space *mapping,
loff_t lstart, loff_t lend)
{ int err = 0, err2;
if (lend < lstart) return 0;
if (mapping_needs_writeback(mapping)) {
err = __filemap_fdatawrite_range(mapping, lstart, lend,
WB_SYNC_ALL); /* * Even if the above returned error, the pages may be * written partially (e.g. -ENOSPC), so we wait for it. * But the -EIO is special case, it may indicate the worst * thing (e.g. bug) happened, so we avoid waiting for it.
*/ if (err != -EIO)
__filemap_fdatawait_range(mapping, lstart, lend);
}
err2 = filemap_check_errors(mapping); if (!err)
err = err2; return err;
}
EXPORT_SYMBOL(filemap_write_and_wait_range);
/** * file_check_and_advance_wb_err - report wb error (if any) that was previously * and advance wb_err to current one * @file: struct file on which the error is being reported * * When userland calls fsync (or something like nfsd does the equivalent), we * want to report any writeback errors that occurred since the last fsync (or * since the file was opened if there haven't been any). * * Grab the wb_err from the mapping. If it matches what we have in the file, * then just quickly return 0. The file is all caught up. * * If it doesn't match, then take the mapping value, set the "seen" flag in * it and try to swap it into place. If it works, or another task beat us * to it with the new value, then update the f_wb_err and return the error * portion. The error at this point must be reported via proper channels * (a'la fsync, or NFS COMMIT operation, etc.). * * While we handle mapping->wb_err with atomic operations, the f_wb_err * value is protected by the f_lock since we must ensure that it reflects * the latest value swapped in for this file descriptor. * * Return: %0 on success, negative error code otherwise.
*/ int file_check_and_advance_wb_err(struct file *file)
{ int err = 0;
errseq_t old = READ_ONCE(file->f_wb_err); struct address_space *mapping = file->f_mapping;
/* Locklessly handle the common case where nothing has changed */ if (errseq_check(&mapping->wb_err, old)) { /* Something changed, must use slow path */
spin_lock(&file->f_lock);
old = file->f_wb_err;
err = errseq_check_and_advance(&mapping->wb_err,
&file->f_wb_err);
trace_file_check_and_advance_wb_err(file, old);
spin_unlock(&file->f_lock);
}
/* * We're mostly using this function as a drop in replacement for * filemap_check_errors. Clear AS_EIO/AS_ENOSPC to emulate the effect * that the legacy code would have had on these flags.
*/
clear_bit(AS_EIO, &mapping->flags);
clear_bit(AS_ENOSPC, &mapping->flags); return err;
}
EXPORT_SYMBOL(file_check_and_advance_wb_err);
/** * file_write_and_wait_range - write out & wait on a file range * @file: file pointing to address_space with pages * @lstart: offset in bytes where the range starts * @lend: offset in bytes where the range ends (inclusive) * * Write out and wait upon file offsets lstart->lend, inclusive. * * Note that @lend is inclusive (describes the last byte to be written) so * that this function can be used to write to the very end-of-file (end = -1). * * After writing out and waiting on the data, we check and advance the * f_wb_err cursor to the latest value, and return any errors detected there. * * Return: %0 on success, negative error code otherwise.
*/ int file_write_and_wait_range(struct file *file, loff_t lstart, loff_t lend)
{ int err = 0, err2; struct address_space *mapping = file->f_mapping;
if (lend < lstart) return 0;
if (mapping_needs_writeback(mapping)) {
err = __filemap_fdatawrite_range(mapping, lstart, lend,
WB_SYNC_ALL); /* See comment of filemap_write_and_wait() */ if (err != -EIO)
__filemap_fdatawait_range(mapping, lstart, lend);
}
err2 = file_check_and_advance_wb_err(file); if (!err)
err = err2; return err;
}
EXPORT_SYMBOL(file_write_and_wait_range);
/** * replace_page_cache_folio - replace a pagecache folio with a new one * @old: folio to be replaced * @new: folio to replace with * * This function replaces a folio in the pagecache with a new one. On * success it acquires the pagecache reference for the new folio and * drops it for the old folio. Both the old and new folios must be * locked. This function does not add the new folio to the LRU, the * caller must do that. * * The remove + add is atomic. This function cannot fail.
*/ void replace_page_cache_folio(struct folio *old, struct folio *new)
{ struct address_space *mapping = old->mapping; void (*free_folio)(struct folio *) = mapping->a_ops->free_folio;
pgoff_t offset = old->index;
XA_STATE(xas, &mapping->i_pages, offset);
old->mapping = NULL; /* hugetlb pages do not participate in page cache accounting. */ if (!folio_test_hugetlb(old))
__lruvec_stat_sub_folio(old, NR_FILE_PAGES); if (!folio_test_hugetlb(new))
__lruvec_stat_add_folio(new, NR_FILE_PAGES); if (folio_test_swapbacked(old))
__lruvec_stat_sub_folio(old, NR_SHMEM); if (folio_test_swapbacked(new))
__lruvec_stat_add_folio(new, NR_SHMEM);
xas_unlock_irq(&xas); if (free_folio)
free_folio(old);
folio_put(old);
}
EXPORT_SYMBOL_GPL(replace_page_cache_folio);
for (;;) { int order = -1; void *entry, *old = NULL;
xas_lock_irq(&xas);
xas_for_each_conflict(&xas, entry) {
old = entry; if (!xa_is_value(entry)) {
xas_set_err(&xas, -EEXIST); goto unlock;
} /* * If a larger entry exists, * it will be the first and only entry iterated.
*/ if (order == -1)
order = xas_get_order(&xas);
}
if (old) { if (order > 0 && order > forder) { unsignedint split_order = max(forder,
xas_try_split_min_order(order));
/* How to handle large swap entries? */
BUG_ON(shmem_mapping(mapping));
while (order > forder) {
xas_set_order(&xas, index, split_order);
xas_try_split(&xas, old, order); if (xas_error(&xas)) goto unlock;
order = split_order;
split_order =
max(xas_try_split_min_order(
split_order),
forder);
}
xas_reset(&xas);
} if (shadowp)
*shadowp = old;
}
xas_store(&xas, folio); if (xas_error(&xas)) goto unlock;
mapping->nrpages += nr;
/* hugetlb pages do not participate in page cache accounting */ if (!huge) {
__lruvec_stat_mod_folio(folio, NR_FILE_PAGES, nr); if (folio_test_pmd_mappable(folio))
__lruvec_stat_mod_folio(folio,
NR_FILE_THPS, nr);
}
int filemap_add_folio(struct address_space *mapping, struct folio *folio,
pgoff_t index, gfp_t gfp)
{ void *shadow = NULL; int ret;
ret = mem_cgroup_charge(folio, NULL, gfp); if (ret) return ret;
__folio_set_locked(folio);
ret = __filemap_add_folio(mapping, folio, index, gfp, &shadow); if (unlikely(ret)) {
mem_cgroup_uncharge(folio);
__folio_clear_locked(folio);
} else { /* * The folio might have been evicted from cache only * recently, in which case it should be activated like * any other repeatedly accessed folio. * The exception is folios getting rewritten; evicting other * data from the working set, only to cache data that will * get overwritten with something else, is a waste of memory.
*/
WARN_ON_ONCE(folio_test_active(folio)); if (!(gfp & __GFP_WRITE) && shadow)
workingset_refault(folio, shadow);
folio_add_lru(folio);
} return ret;
}
EXPORT_SYMBOL_GPL(filemap_add_folio);
/* * filemap_invalidate_lock_two - lock invalidate_lock for two mappings * * Lock exclusively invalidate_lock of any passed mapping that is not NULL. * * @mapping1: the first mapping to lock * @mapping2: the second mapping to lock
*/ void filemap_invalidate_lock_two(struct address_space *mapping1, struct address_space *mapping2)
{ if (mapping1 > mapping2)
swap(mapping1, mapping2); if (mapping1)
down_write(&mapping1->invalidate_lock); if (mapping2 && mapping1 != mapping2)
down_write_nested(&mapping2->invalidate_lock, 1);
}
EXPORT_SYMBOL(filemap_invalidate_lock_two);
/* * filemap_invalidate_unlock_two - unlock invalidate_lock for two mappings * * Unlock exclusive invalidate_lock of any passed mapping that is not NULL. * * @mapping1: the first mapping to unlock * @mapping2: the second mapping to unlock
*/ void filemap_invalidate_unlock_two(struct address_space *mapping1, struct address_space *mapping2)
{ if (mapping1)
up_write(&mapping1->invalidate_lock); if (mapping2 && mapping1 != mapping2)
up_write(&mapping2->invalidate_lock);
}
EXPORT_SYMBOL(filemap_invalidate_unlock_two);
/* * In order to wait for pages to become available there must be * waitqueues associated with pages. By using a hash table of * waitqueues where the bucket discipline is to maintain all * waiters on the same queue and wake all when any of the pages * become available, and for the woken contexts to check to be * sure the appropriate page became available, this saves space * at a cost of "thundering herd" phenomena during rare hash * collisions.
*/ #define PAGE_WAIT_TABLE_BITS 8 #define PAGE_WAIT_TABLE_SIZE (1 << PAGE_WAIT_TABLE_BITS) static wait_queue_head_t folio_wait_table[PAGE_WAIT_TABLE_SIZE] __cacheline_aligned;
/* * The page wait code treats the "wait->flags" somewhat unusually, because * we have multiple different kinds of waits, not just the usual "exclusive" * one. * * We have: * * (a) no special bits set: * * We're just waiting for the bit to be released, and when a waker * calls the wakeup function, we set WQ_FLAG_WOKEN and wake it up, * and remove it from the wait queue. * * Simple and straightforward. * * (b) WQ_FLAG_EXCLUSIVE: * * The waiter is waiting to get the lock, and only one waiter should * be woken up to avoid any thundering herd behavior. We'll set the * WQ_FLAG_WOKEN bit, wake it up, and remove it from the wait queue. * * This is the traditional exclusive wait. * * (c) WQ_FLAG_EXCLUSIVE | WQ_FLAG_CUSTOM: * * The waiter is waiting to get the bit, and additionally wants the * lock to be transferred to it for fair lock behavior. If the lock * cannot be taken, we stop walking the wait queue without waking * the waiter. * * This is the "fair lock handoff" case, and in addition to setting * WQ_FLAG_WOKEN, we set WQ_FLAG_DONE to let the waiter easily see * that it now has the lock.
*/ staticint wake_page_function(wait_queue_entry_t *wait, unsigned mode, int sync, void *arg)
{ unsignedint flags; struct wait_page_key *key = arg; struct wait_page_queue *wait_page
= container_of(wait, struct wait_page_queue, wait);
if (!wake_page_match(wait_page, key)) return 0;
/* * If it's a lock handoff wait, we get the bit for it, and * stop walking (and do not wake it up) if we can't.
*/
flags = wait->flags; if (flags & WQ_FLAG_EXCLUSIVE) { if (test_bit(key->bit_nr, &key->folio->flags)) return -1; if (flags & WQ_FLAG_CUSTOM) { if (test_and_set_bit(key->bit_nr, &key->folio->flags)) return -1;
flags |= WQ_FLAG_DONE;
}
}
/* * We are holding the wait-queue lock, but the waiter that * is waiting for this will be checking the flags without * any locking. * * So update the flags atomically, and wake up the waiter * afterwards to avoid any races. This store-release pairs * with the load-acquire in folio_wait_bit_common().
*/
smp_store_release(&wait->flags, flags | WQ_FLAG_WOKEN);
wake_up_state(wait->private, mode);
/* * Ok, we have successfully done what we're waiting for, * and we can unconditionally remove the wait entry. * * Note that this pairs with the "finish_wait()" in the * waiter, and has to be the absolute last thing we do. * After this list_del_init(&wait->entry) the wait entry * might be de-allocated and the process might even have * exited.
*/
list_del_init_careful(&wait->entry); return (flags & WQ_FLAG_EXCLUSIVE) != 0;
}
/* * It's possible to miss clearing waiters here, when we woke our page * waiters, but the hashed waitqueue has waiters for other pages on it. * That's okay, it's a rare case. The next waker will clear it. * * Note that, depending on the page pool (buddy, hugetlb, ZONE_DEVICE, * other), the flag may be cleared in the course of freeing the page; * but that is not required for correctness.
*/ if (!waitqueue_active(q) || !key.page_match)
folio_clear_waiters(folio);
spin_unlock_irqrestore(&q->lock, flags);
}
/* * A choice of three behaviors for folio_wait_bit_common():
*/ enum behavior {
EXCLUSIVE, /* Hold ref to page and take the bit when woken, like * __folio_lock() waiting on then setting PG_locked.
*/
SHARED, /* Hold ref to page and check the bit when woken, like * folio_wait_writeback() waiting on PG_writeback.
*/
DROP, /* Drop ref to page before wait, no check when woken, * like folio_put_wait_locked() on PG_locked.
*/
};
/* * Attempt to check (or get) the folio flag, and mark us done * if successful.
*/ staticinlinebool folio_trylock_flag(struct folio *folio, int bit_nr, struct wait_queue_entry *wait)
{ if (wait->flags & WQ_FLAG_EXCLUSIVE) { if (test_and_set_bit(bit_nr, &folio->flags)) returnfalse;
} elseif (test_bit(bit_nr, &folio->flags)) returnfalse;
repeat:
wait->flags = 0; if (behavior == EXCLUSIVE) {
wait->flags = WQ_FLAG_EXCLUSIVE; if (--unfairness < 0)
wait->flags |= WQ_FLAG_CUSTOM;
}
/* * Do one last check whether we can get the * page bit synchronously. * * Do the folio_set_waiters() marking before that * to let any waker we _just_ missed know they * need to wake us up (otherwise they'll never * even go to the slow case that looks at the * page queue), and add ourselves to the wait * queue if we need to sleep. * * This part needs to be done under the queue * lock to avoid races.
*/
spin_lock_irq(&q->lock);
folio_set_waiters(folio); if (!folio_trylock_flag(folio, bit_nr, wait))
__add_wait_queue_entry_tail(q, wait);
spin_unlock_irq(&q->lock);
/* * From now on, all the logic will be based on * the WQ_FLAG_WOKEN and WQ_FLAG_DONE flag, to * see whether the page bit testing has already * been done by the wake function. * * We can drop our reference to the folio.
*/ if (behavior == DROP)
folio_put(folio);
/* * Note that until the "finish_wait()", or until * we see the WQ_FLAG_WOKEN flag, we need to * be very careful with the 'wait->flags', because * we may race with a waker that sets them.
*/ for (;;) { unsignedint flags;
set_current_state(state);
/* Loop until we've been woken or interrupted */
flags = smp_load_acquire(&wait->flags); if (!(flags & WQ_FLAG_WOKEN)) { if (signal_pending_state(state, current)) break;
io_schedule(); continue;
}
/* If we were non-exclusive, we're done */ if (behavior != EXCLUSIVE) break;
/* If the waker got the lock for us, we're done */ if (flags & WQ_FLAG_DONE) break;
/* * Otherwise, if we're getting the lock, we need to * try to get it ourselves. * * And if that fails, we'll have to retry this all.
*/ if (unlikely(test_and_set_bit(bit_nr, folio_flags(folio, 0)))) goto repeat;
wait->flags |= WQ_FLAG_DONE; break;
}
/* * If a signal happened, this 'finish_wait()' may remove the last * waiter from the wait-queues, but the folio waiters bit will remain * set. That's ok. The next wakeup will take care of it, and trying * to do it here would be difficult and prone to races.
*/
finish_wait(q, wait);
if (thrashing) {
delayacct_thrashing_end(&in_thrashing);
psi_memstall_leave(&pflags);
}
/* * NOTE! The wait->flags weren't stable until we've done the * 'finish_wait()', and we could have exited the loop above due * to a signal, and had a wakeup event happen after the signal * test but before the 'finish_wait()'. * * So only after the finish_wait() can we reliably determine * if we got woken up or not, so we can now figure out the final * return value based on that state without races. * * Also note that WQ_FLAG_WOKEN is sufficient for a non-exclusive * waiter, but an exclusive one requires WQ_FLAG_DONE.
*/ if (behavior == EXCLUSIVE) return wait->flags & WQ_FLAG_DONE ? 0 : -EINTR;
#ifdef CONFIG_MIGRATION /** * migration_entry_wait_on_locked - Wait for a migration entry to be removed * @entry: migration swap entry. * @ptl: already locked ptl. This function will drop the lock. * * Wait for a migration entry referencing the given page to be removed. This is * equivalent to folio_put_wait_locked(folio, TASK_UNINTERRUPTIBLE) except * this can be called without taking a reference on the page. Instead this * should be called while holding the ptl for the migration entry referencing * the page. * * Returns after unlocking the ptl. * * This follows the same logic as folio_wait_bit_common() so see the comments * there.
*/ void migration_entry_wait_on_locked(swp_entry_t entry, spinlock_t *ptl)
__releases(ptl)
{ struct wait_page_queue wait_page;
wait_queue_entry_t *wait = &wait_page.wait; bool thrashing = false; unsignedlong pflags; bool in_thrashing;
wait_queue_head_t *q; struct folio *folio = pfn_swap_entry_folio(entry);
spin_lock_irq(&q->lock);
folio_set_waiters(folio); if (!folio_trylock_flag(folio, PG_locked, wait))
__add_wait_queue_entry_tail(q, wait);
spin_unlock_irq(&q->lock);
/* * If a migration entry exists for the page the migration path must hold * a valid reference to the page, and it must take the ptl to remove the * migration entry. So the page is valid until the ptl is dropped.
*/
spin_unlock(ptl);
for (;;) { unsignedint flags;
set_current_state(TASK_UNINTERRUPTIBLE);
/* Loop until we've been woken or interrupted */
flags = smp_load_acquire(&wait->flags); if (!(flags & WQ_FLAG_WOKEN)) { if (signal_pending_state(TASK_UNINTERRUPTIBLE, current)) break;
io_schedule(); continue;
} break;
}
finish_wait(q, wait);
if (thrashing) {
delayacct_thrashing_end(&in_thrashing);
psi_memstall_leave(&pflags);
}
} #endif
int folio_wait_bit_killable(struct folio *folio, int bit_nr)
{ return folio_wait_bit_common(folio, bit_nr, TASK_KILLABLE, SHARED);
}
EXPORT_SYMBOL(folio_wait_bit_killable);
/** * folio_put_wait_locked - Drop a reference and wait for it to be unlocked * @folio: The folio to wait for. * @state: The sleep state (TASK_KILLABLE, TASK_UNINTERRUPTIBLE, etc). * * The caller should hold a reference on @folio. They expect the page to * become unlocked relatively soon, but do not wish to hold up migration * (for example) by holding the reference while waiting for the folio to * come unlocked. After this function returns, the caller should not * dereference @folio. * * Return: 0 if the folio was unlocked or -EINTR if interrupted by a signal.
*/ staticint folio_put_wait_locked(struct folio *folio, int state)
{ return folio_wait_bit_common(folio, PG_locked, state, DROP);
}
/** * folio_unlock - Unlock a locked folio. * @folio: The folio. * * Unlocks the folio and wakes up any thread sleeping on the page lock. * * Context: May be called from interrupt or process context. May not be * called from NMI context.
*/ void folio_unlock(struct folio *folio)
{ /* Bit 7 allows x86 to check the byte's sign bit */
BUILD_BUG_ON(PG_waiters != 7);
BUILD_BUG_ON(PG_locked > 7);
VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); if (folio_xor_flags_has_waiters(folio, 1 << PG_locked))
folio_wake_bit(folio, PG_locked);
}
EXPORT_SYMBOL(folio_unlock);
/** * folio_end_read - End read on a folio. * @folio: The folio. * @success: True if all reads completed successfully. * * When all reads against a folio have completed, filesystems should * call this function to let the pagecache know that no more reads * are outstanding. This will unlock the folio and wake up any thread * sleeping on the lock. The folio will also be marked uptodate if all * reads succeeded. * * Context: May be called from interrupt or process context. May not be * called from NMI context.
*/ void folio_end_read(struct folio *folio, bool success)
{ unsignedlong mask = 1 << PG_locked;
/* Must be in bottom byte for x86 to work */
BUILD_BUG_ON(PG_uptodate > 7);
VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
VM_BUG_ON_FOLIO(success && folio_test_uptodate(folio), folio);
if (likely(success))
mask |= 1 << PG_uptodate; if (folio_xor_flags_has_waiters(folio, mask))
folio_wake_bit(folio, PG_locked);
}
EXPORT_SYMBOL(folio_end_read);
/** * folio_end_private_2 - Clear PG_private_2 and wake any waiters. * @folio: The folio. * * Clear the PG_private_2 bit on a folio and wake up any sleepers waiting for * it. The folio reference held for PG_private_2 being set is released. * * This is, for example, used when a netfs folio is being written to a local * disk cache, thereby allowing writes to the cache for the same folio to be * serialised.
*/ void folio_end_private_2(struct folio *folio)
{
VM_BUG_ON_FOLIO(!folio_test_private_2(folio), folio);
clear_bit_unlock(PG_private_2, folio_flags(folio, 0));
folio_wake_bit(folio, PG_private_2);
folio_put(folio);
}
EXPORT_SYMBOL(folio_end_private_2);
/** * folio_wait_private_2 - Wait for PG_private_2 to be cleared on a folio. * @folio: The folio to wait on. * * Wait for PG_private_2 to be cleared on a folio.
*/ void folio_wait_private_2(struct folio *folio)
{ while (folio_test_private_2(folio))
folio_wait_bit(folio, PG_private_2);
}
EXPORT_SYMBOL(folio_wait_private_2);
/** * folio_wait_private_2_killable - Wait for PG_private_2 to be cleared on a folio. * @folio: The folio to wait on. * * Wait for PG_private_2 to be cleared on a folio or until a fatal signal is * received by the calling task. * * Return: * - 0 if successful. * - -EINTR if a fatal signal was encountered.
*/ int folio_wait_private_2_killable(struct folio *folio)
{ int ret = 0;
while (folio_test_private_2(folio)) {
ret = folio_wait_bit_killable(folio, PG_private_2); if (ret < 0) break;
}
if (folio_test_writeback(folio) || folio_test_dirty(folio)) return; if (!folio_test_clear_dropbehind(folio)) return; if (mapping)
folio_unmap_invalidate(mapping, folio, 0);
}
/* * If folio was marked as dropbehind, then pages should be dropped when writeback * completes. Do that now. If we fail, it's likely because of a big folio - * just reset dropbehind for that case and latter completions should invalidate.
*/ staticvoid filemap_end_dropbehind_write(struct folio *folio)
{ if (!folio_test_dropbehind(folio)) return;
/* * Hitting !in_task() should not happen off RWF_DONTCACHE writeback, * but can happen if normal writeback just happens to find dirty folios * that were created as part of uncached writeback, and that writeback * would otherwise not need non-IRQ handling. Just skip the * invalidation in that case.
*/ if (in_task() && folio_trylock(folio)) {
filemap_end_dropbehind(folio);
folio_unlock(folio);
}
}
/** * folio_end_writeback - End writeback against a folio. * @folio: The folio. * * The folio must actually be under writeback. * * Context: May be called from process or interrupt context.
*/ void folio_end_writeback(struct folio *folio)
{
VM_BUG_ON_FOLIO(!folio_test_writeback(folio), folio);
/* * folio_test_clear_reclaim() could be used here but it is an * atomic operation and overkill in this particular case. Failing * to shuffle a folio marked for immediate reclaim is too mild * a gain to justify taking an atomic operation penalty at the * end of every folio writeback.
*/ if (folio_test_reclaim(folio)) {
folio_clear_reclaim(folio);
folio_rotate_reclaimable(folio);
}
/* * Writeback does not hold a folio reference of its own, relying * on truncation to wait for the clearing of PG_writeback. * But here we must make sure that the folio is not freed and * reused before the folio_wake_bit().
*/
folio_get(folio); if (__folio_end_writeback(folio))
folio_wake_bit(folio, PG_writeback);
/** * __folio_lock - Get a lock on the folio, assuming we need to sleep to get it. * @folio: The folio to lock
*/ void __folio_lock(struct folio *folio)
{
folio_wait_bit_common(folio, PG_locked, TASK_UNINTERRUPTIBLE,
EXCLUSIVE);
}
EXPORT_SYMBOL(__folio_lock);
spin_lock_irq(&q->lock);
__add_wait_queue_entry_tail(q, &wait->wait);
folio_set_waiters(folio);
ret = !folio_trylock(folio); /* * If we were successful now, we know we're still on the * waitqueue as we're still under the lock. This means it's * safe to remove and return success, we know the callback * isn't going to trigger.
*/ if (!ret)
__remove_wait_queue(q, &wait->wait); else
ret = -EIOCBQUEUED;
spin_unlock_irq(&q->lock); return ret;
}
/* * Return values: * 0 - folio is locked. * non-zero - folio is not locked. * mmap_lock or per-VMA lock has been released (mmap_read_unlock() or * vma_end_read()), unless flags had both FAULT_FLAG_ALLOW_RETRY and * FAULT_FLAG_RETRY_NOWAIT set, in which case the lock is still held. * * If neither ALLOW_RETRY nor KILLABLE are set, will always return 0 * with the folio locked and the mmap_lock/per-VMA lock is left unperturbed.
*/
vm_fault_t __folio_lock_or_retry(struct folio *folio, struct vm_fault *vmf)
{ unsignedint flags = vmf->flags;
if (fault_flag_allow_retry_first(flags)) { /* * CAUTION! In this case, mmap_lock/per-VMA lock is not * released even though returning VM_FAULT_RETRY.
*/ if (flags & FAULT_FLAG_RETRY_NOWAIT) return VM_FAULT_RETRY;
release_fault_lock(vmf); if (flags & FAULT_FLAG_KILLABLE)
folio_wait_locked_killable(folio); else
folio_wait_locked(folio); return VM_FAULT_RETRY;
} if (flags & FAULT_FLAG_KILLABLE) { bool ret;
ret = __folio_lock_killable(folio); if (ret) {
release_fault_lock(vmf); return VM_FAULT_RETRY;
}
} else {
__folio_lock(folio);
}
return 0;
}
/** * page_cache_next_miss() - Find the next gap in the page cache. * @mapping: Mapping. * @index: Index. * @max_scan: Maximum range to search. * * Search the range [index, min(index + max_scan - 1, ULONG_MAX)] for the * gap with the lowest index. * * This function may be called under the rcu_read_lock. However, this will * not atomically search a snapshot of the cache at a single point in time. * For example, if a gap is created at index 5, then subsequently a gap is * created at index 10, page_cache_next_miss covering both indices may * return 10 if called under the rcu_read_lock. * * Return: The index of the gap if found, otherwise an index outside the * range specified (in which case 'return - index >= max_scan' will be true). * In the rare case of index wrap-around, 0 will be returned.
*/
pgoff_t page_cache_next_miss(struct address_space *mapping,
pgoff_t index, unsignedlong max_scan)
{
XA_STATE(xas, &mapping->i_pages, index); unsignedlong nr = max_scan;
while (nr--) { void *entry = xas_next(&xas); if (!entry || xa_is_value(entry)) return xas.xa_index; if (xas.xa_index == 0) return 0;
}
return index + max_scan;
}
EXPORT_SYMBOL(page_cache_next_miss);
/** * page_cache_prev_miss() - Find the previous gap in the page cache. * @mapping: Mapping. * @index: Index. * @max_scan: Maximum range to search. * * Search the range [max(index - max_scan + 1, 0), index] for the * gap with the highest index. * * This function may be called under the rcu_read_lock. However, this will * not atomically search a snapshot of the cache at a single point in time. * For example, if a gap is created at index 10, then subsequently a gap is * created at index 5, page_cache_prev_miss() covering both indices may * return 5 if called under the rcu_read_lock. * * Return: The index of the gap if found, otherwise an index outside the * range specified (in which case 'index - return >= max_scan' will be true). * In the rare case of wrap-around, ULONG_MAX will be returned.
*/
pgoff_t page_cache_prev_miss(struct address_space *mapping,
pgoff_t index, unsignedlong max_scan)
{
XA_STATE(xas, &mapping->i_pages, index);
while (max_scan--) { void *entry = xas_prev(&xas); if (!entry || xa_is_value(entry)) break; if (xas.xa_index == ULONG_MAX) break;
}
/* * Lockless page cache protocol: * On the lookup side: * 1. Load the folio from i_pages * 2. Increment the refcount if it's not zero * 3. If the folio is not found by xas_reload(), put the refcount and retry * * On the removal side: * A. Freeze the page (by zeroing the refcount if nobody else has a reference) * B. Remove the page from i_pages * C. Return the page to the page allocator * * This means that any page may have its reference count temporarily * increased by a speculative page cache (or GUP-fast) lookup as it can * be allocated by another user before the RCU grace period expires. * Because the refcount temporarily acquired here may end up being the * last refcount on the page, any page allocation must be freeable by * folio_put().
*/
/* * filemap_get_entry - Get a page cache entry. * @mapping: the address_space to search * @index: The page cache index. * * Looks up the page cache entry at @mapping & @index. If it is a folio, * it is returned with an increased refcount. If it is a shadow entry * of a previously evicted folio, or a swap entry from shmem/tmpfs, * it is returned without further action. * * Return: The folio, swap or shadow entry, %NULL if nothing is found.
*/ void *filemap_get_entry(struct address_space *mapping, pgoff_t index)
{
XA_STATE(xas, &mapping->i_pages, index); struct folio *folio;
rcu_read_lock();
repeat:
xas_reset(&xas);
folio = xas_load(&xas); if (xas_retry(&xas, folio)) goto repeat; /* * A shadow entry of a recently evicted page, or a swap entry from * shmem/tmpfs. Return it without attempting to raise page count.
*/ if (!folio || xa_is_value(folio)) goto out;
/** * __filemap_get_folio - Find and get a reference to a folio. * @mapping: The address_space to search. * @index: The page index. * @fgp_flags: %FGP flags modify how the folio is returned. * @gfp: Memory allocation flags to use if %FGP_CREAT is specified. * * Looks up the page cache entry at @mapping & @index. * * If %FGP_LOCK or %FGP_CREAT are specified then the function may sleep even * if the %GFP flags specified for %FGP_CREAT are atomic. * * If this function returns a folio, it is returned with an increased refcount. * * Return: The found folio or an ERR_PTR() otherwise.
*/ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
fgf_t fgp_flags, gfp_t gfp)
{ struct folio *folio;
repeat:
folio = filemap_get_entry(mapping, index); if (xa_is_value(folio))
folio = NULL; if (!folio) goto no_page;
if (fgp_flags & FGP_LOCK) { if (fgp_flags & FGP_NOWAIT) { if (!folio_trylock(folio)) {
folio_put(folio); return ERR_PTR(-EAGAIN);
}
} else {
folio_lock(folio);
}
/* Has the page been truncated? */ if (unlikely(folio->mapping != mapping)) {
folio_unlock(folio);
folio_put(folio); goto repeat;
}
VM_BUG_ON_FOLIO(!folio_contains(folio, index), folio);
}
if (fgp_flags & FGP_ACCESSED)
folio_mark_accessed(folio); elseif (fgp_flags & FGP_WRITE) { /* Clear idle flag for buffer write */ if (folio_test_idle(folio))
folio_clear_idle(folio);
}
if (fgp_flags & FGP_STABLE)
folio_wait_stable(folio);
no_page: if (!folio && (fgp_flags & FGP_CREAT)) { unsignedint min_order = mapping_min_folio_order(mapping); unsignedint order = max(min_order, FGF_GET_ORDER(fgp_flags)); int err;
index = mapping_align_index(mapping, index);
if ((fgp_flags & FGP_WRITE) && mapping_can_writeback(mapping))
gfp |= __GFP_WRITE; if (fgp_flags & FGP_NOFS)
gfp &= ~__GFP_FS; if (fgp_flags & FGP_NOWAIT) {
gfp &= ~GFP_KERNEL;
gfp |= GFP_NOWAIT | __GFP_NOWARN;
} if (WARN_ON_ONCE(!(fgp_flags & (FGP_LOCK | FGP_FOR_MMAP))))
fgp_flags |= FGP_LOCK;
if (order > mapping_max_folio_order(mapping))
order = mapping_max_folio_order(mapping); /* If we're not aligned, allocate a smaller folio */ if (index & ((1UL << order) - 1))
order = __ffs(index);
do {
gfp_t alloc_gfp = gfp;
err = -ENOMEM; if (order > min_order)
alloc_gfp |= __GFP_NORETRY | __GFP_NOWARN;
folio = filemap_alloc_folio(alloc_gfp, order); if (!folio) continue;
/* Init accessed so avoid atomic mark_page_accessed later */ if (fgp_flags & FGP_ACCESSED)
__folio_set_referenced(folio); if (fgp_flags & FGP_DONTCACHE)
__folio_set_dropbehind(folio);
err = filemap_add_folio(mapping, folio, index, gfp); if (!err) break;
folio_put(folio);
folio = NULL;
} while (order-- > min_order);
if (err == -EEXIST) goto repeat; if (err) { /* * When NOWAIT I/O fails to allocate folios this could * be due to a nonblocking memory allocation and not * because the system actually is out of memory. * Return -EAGAIN so that there caller retries in a * blocking fashion instead of propagating -ENOMEM * to the application.
*/ if ((fgp_flags & FGP_NOWAIT) && err == -ENOMEM)
err = -EAGAIN; return ERR_PTR(err);
} /* * filemap_add_folio locks the page, and for mmap * we expect an unlocked page.
*/ if (folio && (fgp_flags & FGP_FOR_MMAP))
folio_unlock(folio);
}
if (!folio) return ERR_PTR(-ENOENT); /* not an uncached lookup, clear uncached if set */ if (folio_test_dropbehind(folio) && !(fgp_flags & FGP_DONTCACHE))
folio_clear_dropbehind(folio); return folio;
}
EXPORT_SYMBOL(__filemap_get_folio);
if (xas_retry(xas, folio)) goto retry; /* * A shadow entry of a recently evicted page, a swap * entry from shmem/tmpfs or a DAX entry. Return it * without attempting to raise page count.
*/ if (!folio || xa_is_value(folio)) return folio;
if (!folio_try_get(folio)) goto reset;
if (unlikely(folio != xas_reload(xas))) {
folio_put(folio); goto reset;
}
/** * find_get_entries - gang pagecache lookup * @mapping: The address_space to search * @start: The starting page cache index * @end: The final page index (inclusive). * @fbatch: Where the resulting entries are placed. * @indices: The cache indices corresponding to the entries in @entries * * find_get_entries() will search for and return a batch of entries in * the mapping. The entries are placed in @fbatch. find_get_entries() * takes a reference on any actual folios it returns. * * The entries have ascending indexes. The indices may not be consecutive * due to not-present entries or large folios. * * Any shadow entries of evicted folios, or swap entries from * shmem/tmpfs, are included in the returned array. * * Return: The number of entries which were found.
*/ unsigned find_get_entries(struct address_space *mapping, pgoff_t *start,
pgoff_t end, struct folio_batch *fbatch, pgoff_t *indices)
{
XA_STATE(xas, &mapping->i_pages, *start); struct folio *folio;
rcu_read_lock(); while ((folio = find_get_entry(&xas, end, XA_PRESENT)) != NULL) {
indices[fbatch->nr] = xas.xa_index; if (!folio_batch_add(fbatch, folio)) break;
}
if (folio_batch_count(fbatch)) { unsignedlong nr; int idx = folio_batch_count(fbatch) - 1;
folio = fbatch->folios[idx]; if (!xa_is_value(folio))
nr = folio_nr_pages(folio); else
nr = 1 << xa_get_order(&mapping->i_pages, indices[idx]);
*start = round_down(indices[idx] + nr, nr);
}
rcu_read_unlock();
return folio_batch_count(fbatch);
}
/** * find_lock_entries - Find a batch of pagecache entries. * @mapping: The address_space to search. * @start: The starting page cache index. * @end: The final page index (inclusive). * @fbatch: Where the resulting entries are placed. * @indices: The cache indices of the entries in @fbatch. * * find_lock_entries() will return a batch of entries from @mapping. * Swap, shadow and DAX entries are included. Folios are returned * locked and with an incremented refcount. Folios which are locked * by somebody else or under writeback are skipped. Folios which are * partially outside the range are not returned. * * The entries have ascending indexes. The indices may not be consecutive * due to not-present entries, large folios, folios which could not be * locked or folios under writeback. * * Return: The number of entries which were found.
*/ unsigned find_lock_entries(struct address_space *mapping, pgoff_t *start,
pgoff_t end, struct folio_batch *fbatch, pgoff_t *indices)
{
XA_STATE(xas, &mapping->i_pages, *start); struct folio *folio;
if (!xa_is_value(folio)) {
nr = folio_nr_pages(folio);
base = folio->index; /* Omit large folio which begins before the start */ if (base < *start) goto put; /* Omit large folio which extends beyond the end */ if (base + nr - 1 > end) goto put; if (!folio_trylock(folio)) goto put; if (folio->mapping != mapping ||
folio_test_writeback(folio)) goto unlock;
VM_BUG_ON_FOLIO(!folio_contains(folio, xas.xa_index),
folio);
} else {
nr = 1 << xas_get_order(&xas);
base = xas.xa_index & ~(nr - 1); /* Omit order>0 value which begins before the start */ if (base < *start) continue; /* Omit order>0 value which extends beyond the end */ if (base + nr - 1 > end) break;
}
/* Update start now so that last update is correct on return */
*start = base + nr;
indices[fbatch->nr] = xas.xa_index; if (!folio_batch_add(fbatch, folio)) break; continue;
unlock:
folio_unlock(folio);
put:
folio_put(folio);
}
rcu_read_unlock();
return folio_batch_count(fbatch);
}
/** * filemap_get_folios - Get a batch of folios * @mapping: The address_space to search * @start: The starting page index * @end: The final page index (inclusive) * @fbatch: The batch to fill. * * Search for and return a batch of folios in the mapping starting at * index @start and up to index @end (inclusive). The folios are returned * in @fbatch with an elevated reference count. * * Return: The number of folios which were found. * We also update @start to index the next folio for the traversal.
*/ unsigned filemap_get_folios(struct address_space *mapping, pgoff_t *start,
pgoff_t end, struct folio_batch *fbatch)
{ return filemap_get_folios_tag(mapping, start, end, XA_PRESENT, fbatch);
}
EXPORT_SYMBOL(filemap_get_folios);
/** * filemap_get_folios_contig - Get a batch of contiguous folios * @mapping: The address_space to search * @start: The starting page index * @end: The final page index (inclusive) * @fbatch: The batch to fill * * filemap_get_folios_contig() works exactly like filemap_get_folios(), * except the returned folios are guaranteed to be contiguous. This may * not return all contiguous folios if the batch gets filled up. * * Return: The number of folios found. * Also update @start to be positioned for traversal of the next folio.
*/
for (folio = xas_load(&xas); folio && xas.xa_index <= end;
folio = xas_next(&xas)) { if (xas_retry(&xas, folio)) continue; /* * If the entry has been swapped out, we can stop looking. * No current caller is looking for DAX entries.
*/ if (xa_is_value(folio)) goto update_start;
/* If we landed in the middle of a THP, continue at its end. */ if (xa_is_sibling(folio)) goto update_start;
if (!folio_try_get(folio)) goto retry;
if (unlikely(folio != xas_reload(&xas))) goto put_folio;
/** * filemap_get_folios_tag - Get a batch of folios matching @tag * @mapping: The address_space to search * @start: The starting page index * @end: The final page index (inclusive) * @tag: The tag index * @fbatch: The batch to fill * * The first folio may start before @start; if it does, it will contain * @start. The final folio may extend beyond @end; if it does, it will * contain @end. The folios have ascending indices. There may be gaps * between the folios if there are indices which have no folio in the * page cache. If folios are added to or removed from the page cache * while this is running, they may or may not be found by this call. * Only returns folios that are tagged with @tag. * * Return: The number of folios found. * Also update @start to index the next folio for traversal.
*/ unsigned filemap_get_folios_tag(struct address_space *mapping, pgoff_t *start,
pgoff_t end, xa_mark_t tag, struct folio_batch *fbatch)
{
XA_STATE(xas, &mapping->i_pages, *start); struct folio *folio;
rcu_read_lock(); while ((folio = find_get_entry(&xas, end, tag)) != NULL) { /* * Shadow entries should never be tagged, but this iteration * is lockless so there is a window for page reclaim to evict * a page we saw tagged. Skip over it.
*/ if (xa_is_value(folio)) continue; if (!folio_batch_add(fbatch, folio)) { unsignedlong nr = folio_nr_pages(folio);
*start = folio->index + nr; goto out;
}
} /* * We come here when there is no page beyond @end. We take care to not * overflow the index @start as it confuses some of the callers. This * breaks the iteration when there is a page at index -1 but that is * already broke anyway.
*/ if (end == (pgoff_t)-1)
*start = (pgoff_t)-1; else
*start = end + 1;
out:
rcu_read_unlock();
/* * CD/DVDs are error prone. When a medium error occurs, the driver may fail * a _large_ part of the i/o request. Imagine the worst scenario: * * ---R__________________________________________B__________ * ^ reading here ^ bad block(assume 4k) * * read(R) => miss => readahead(R...B) => media error => frustrating retries * => failing the whole request => read(R) => read(R+1) => * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) => * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) => * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ...... * * It is going insane. Fix it by quickly scaling down the readahead size.
*/ staticvoid shrink_readahead_size_eio(struct file_ra_state *ra)
{
ra->ra_pages /= 4;
}
/* * filemap_get_read_batch - Get a batch of folios for read * * Get a batch of folios which represent a contiguous range of bytes in * the file. No exceptional entries will be returned. If @index is in * the middle of a folio, the entire folio will be returned. The last * folio in the batch may have the readahead flag set or the uptodate flag * clear so that the caller can take the appropriate action.
*/ staticvoid filemap_get_read_batch(struct address_space *mapping,
pgoff_t index, pgoff_t max, struct folio_batch *fbatch)
{
XA_STATE(xas, &mapping->i_pages, index); struct folio *folio;
rcu_read_lock(); for (folio = xas_load(&xas); folio; folio = xas_next(&xas)) { if (xas_retry(&xas, folio)) continue; if (xas.xa_index > max || xa_is_value(folio)) break; if (xa_is_sibling(folio)) break; if (!folio_try_get(folio)) goto retry;
if (unlikely(folio != xas_reload(&xas))) goto put_folio;
if (!folio_batch_add(fbatch, folio)) break; if (!folio_test_uptodate(folio)) break; if (folio_test_readahead(folio)) break;
xas_advance(&xas, folio_next_index(folio) - 1); continue;
put_folio:
folio_put(folio);
retry:
xas_reset(&xas);
}
rcu_read_unlock();
}
/* Start the actual read. The read will unlock the page. */ if (unlikely(workingset))
psi_memstall_enter(&pflags);
error = filler(file, folio); if (unlikely(workingset))
psi_memstall_leave(&pflags); if (error) return error;
error = folio_wait_locked_killable(folio); if (error) return error; if (folio_test_uptodate(folio)) return 0; if (file)
shrink_readahead_size_eio(&file->f_ra); return -EIO;
}
staticbool filemap_range_uptodate(struct address_space *mapping,
loff_t pos, size_t count, struct folio *folio, bool need_uptodate)
{ if (folio_test_uptodate(folio)) returntrue; /* pipes can't handle partially uptodate pages */ if (need_uptodate) returnfalse; if (!mapping->a_ops->is_partially_uptodate) returnfalse; if (mapping->host->i_blkbits >= folio_shift(folio)) returnfalse;
if (iocb->ki_flags & IOCB_NOWAIT) { if (!filemap_invalidate_trylock_shared(mapping)) return -EAGAIN;
} else {
filemap_invalidate_lock_shared(mapping);
}
if (!folio_trylock(folio)) {
error = -EAGAIN; if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_NOIO)) goto unlock_mapping; if (!(iocb->ki_flags & IOCB_WAITQ)) {
filemap_invalidate_unlock_shared(mapping); /* * This is where we usually end up waiting for a * previously submitted readahead to finish.
*/
folio_put_wait_locked(folio, TASK_KILLABLE); return AOP_TRUNCATED_PAGE;
}
error = __folio_lock_async(folio, iocb->ki_waitq); if (error) goto unlock_mapping;
}
error = AOP_TRUNCATED_PAGE; if (!folio->mapping) goto unlock;
if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_WAITQ)) return -EAGAIN;
folio = filemap_alloc_folio(mapping_gfp_mask(mapping), min_order); if (!folio) return -ENOMEM; if (iocb->ki_flags & IOCB_DONTCACHE)
__folio_set_dropbehind(folio);
/* * Protect against truncate / hole punch. Grabbing invalidate_lock * here assures we cannot instantiate and bring uptodate new * pagecache folios after evicting page cache during truncate * and before actually freeing blocks. Note that we could * release invalidate_lock after inserting the folio into * the page cache as the locked folio would then be enough to * synchronize with hole punching. But there are code paths * such as filemap_update_page() filling in partially uptodate * pages or ->readahead() that need to hold invalidate_lock * while mapping blocks for IO so let's hold the lock here as * well to keep locking rules simple.
*/
filemap_invalidate_lock_shared(mapping);
index = (iocb->ki_pos >> (PAGE_SHIFT + min_order)) << min_order;
error = filemap_add_folio(mapping, folio, index,
mapping_gfp_constraint(mapping, GFP_KERNEL)); if (error == -EEXIST)
error = AOP_TRUNCATED_PAGE; if (error) goto error;
error = filemap_read_folio(iocb->ki_filp, mapping->a_ops->read_folio,
folio); if (error) goto error;
/* "last_index" is the index of the page beyond the end of the read */
last_index = DIV_ROUND_UP(iocb->ki_pos + count, PAGE_SIZE);
retry: if (fatal_signal_pending(current)) return -EINTR;
staticvoid filemap_end_dropbehind_read(struct folio *folio)
{ if (!folio_test_dropbehind(folio)) return; if (folio_test_writeback(folio) || folio_test_dirty(folio)) return; if (folio_trylock(folio)) {
filemap_end_dropbehind(folio);
folio_unlock(folio);
}
}
/** * filemap_read - Read data from the page cache. * @iocb: The iocb to read. * @iter: Destination for the data. * @already_read: Number of bytes already read by the caller. * * Copies data from the page cache. If the data is not currently present, * uses the readahead and read_folio address_space operations to fetch it. * * Return: Total number of bytes copied, including those already read by * the caller. If an error happens before any bytes are copied, returns * a negative error number.
*/
ssize_t filemap_read(struct kiocb *iocb, struct iov_iter *iter,
ssize_t already_read)
{ struct file *filp = iocb->ki_filp; struct file_ra_state *ra = &filp->f_ra; struct address_space *mapping = filp->f_mapping; struct inode *inode = mapping->host; struct folio_batch fbatch; int i, error = 0; bool writably_mapped;
loff_t isize, end_offset;
loff_t last_pos = ra->prev_pos;
if (unlikely(iocb->ki_pos < 0)) return -EINVAL; if (unlikely(iocb->ki_pos >= inode->i_sb->s_maxbytes)) return 0; if (unlikely(!iov_iter_count(iter))) return 0;
/* * If we've already successfully copied some data, then we * can no longer safely return -EIOCBQUEUED. Hence mark * an async read NOWAIT at that point.
*/ if ((iocb->ki_flags & IOCB_WAITQ) && already_read)
iocb->ki_flags |= IOCB_NOWAIT;
if (unlikely(iocb->ki_pos >= i_size_read(inode))) break;
/* * i_size must be checked after we know the pages are Uptodate. * * Checking i_size after the check allows us to calculate * the correct value for "nr", which means the zero-filled * part of the page is not copied back to userspace (unless * another truncate extends the file - this is desired though).
*/
isize = i_size_read(inode); if (unlikely(iocb->ki_pos >= isize)) goto put_folios;
end_offset = min_t(loff_t, isize, iocb->ki_pos + iter->count);
/* * Once we start copying data, we don't want to be touching any * cachelines that might be contended:
*/
writably_mapped = mapping_writably_mapped(mapping);
/* * When a read accesses the same folio several times, only * mark it as accessed the first time.
*/ if (!pos_same_folio(iocb->ki_pos, last_pos - 1,
fbatch.folios[0]))
folio_mark_accessed(fbatch.folios[0]);
if (end_offset < folio_pos(folio)) break; if (i > 0)
folio_mark_accessed(folio); /* * If users can be writing to this folio using arbitrary * virtual addresses, take care of potential aliasing * before reading the folio on the kernel side.
*/ if (writably_mapped)
flush_dcache_folio(folio);
int filemap_invalidate_pages(struct address_space *mapping,
loff_t pos, loff_t end, bool nowait)
{ int ret;
if (nowait) { /* we could block if there are any pages in the range */ if (filemap_range_has_page(mapping, pos, end)) return -EAGAIN;
} else {
ret = filemap_write_and_wait_range(mapping, pos, end); if (ret) return ret;
}
/* * After a write we want buffered reads to be sure to go to disk to get * the new data. We invalidate clean cached page from the region we're * about to write. We do this *before* the write so that we can return * without clobbering -EIOCBQUEUED from ->direct_IO().
*/ return invalidate_inode_pages2_range(mapping, pos >> PAGE_SHIFT,
end >> PAGE_SHIFT);
}
/** * generic_file_read_iter - generic filesystem read routine * @iocb: kernel I/O control block * @iter: destination for the data read * * This is the "read_iter()" routine for all filesystems * that can use the page cache directly. * * The IOCB_NOWAIT flag in iocb->ki_flags indicates that -EAGAIN shall * be returned when no data can be read without waiting for I/O requests * to complete; it doesn't prevent readahead. * * The IOCB_NOIO flag in iocb->ki_flags indicates that no new I/O * requests shall be made for the read or for readahead. When no data * can be read, -EAGAIN shall be returned. When readahead would be * triggered, a partial, possibly empty read shall be returned. * * Return: * * number of bytes copied, even for partial reads * * negative error code (or 0 if IOCB_NOIO) if nothing was read
*/
ssize_t
generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
{
size_t count = iov_iter_count(iter);
ssize_t retval = 0;
/* * Btrfs can have a short DIO read if we encounter * compressed extents, so if there was an error, or if * we've already read everything we wanted to, or if * there was a short read because we hit EOF, go ahead * and return. Otherwise fallthrough to buffered io for * the rest of the read. Buffered reads will not work for * DAX files, so don't bother trying.
*/ if (retval < 0 || !count || IS_DAX(inode)) return retval; if (iocb->ki_pos >= i_size_read(inode)) return retval;
}
/** * filemap_splice_read - Splice data from a file's pagecache into a pipe * @in: The file to read from * @ppos: Pointer to the file position to read from * @pipe: The pipe to splice into * @len: The amount to splice * @flags: The SPLICE_F_* flags * * This function gets folios from a file's pagecache and splices them into the * pipe. Readahead will be called as necessary to fill more folios. This may * be used for blockdevs also. * * Return: On success, the number of bytes read will be returned and *@ppos * will be updated if appropriate; 0 will be returned if there is no more data * to be read; -EAGAIN will be returned if the pipe had no space, and some * other negative error code will be returned on error. A short read may occur * if the pipe has insufficient space, we reach the end of the data or we hit a * hole.
*/
ssize_t filemap_splice_read(struct file *in, loff_t *ppos, struct pipe_inode_info *pipe,
size_t len, unsignedint flags)
{ struct folio_batch fbatch; struct kiocb iocb;
size_t total_spliced = 0, used, npages;
loff_t isize, end_offset; bool writably_mapped; int i, error = 0;
if (unlikely(*ppos >= in->f_mapping->host->i_sb->s_maxbytes)) return 0;
init_sync_kiocb(&iocb, in);
iocb.ki_pos = *ppos;
/* Work out how much data we can actually add into the pipe */
used = pipe_buf_usage(pipe);
npages = max_t(ssize_t, pipe->max_usage - used, 0);
len = min_t(size_t, len, npages * PAGE_SIZE);
folio_batch_init(&fbatch);
do {
cond_resched();
if (*ppos >= i_size_read(in->f_mapping->host)) break;
/* * i_size must be checked after we know the pages are Uptodate. * * Checking i_size after the check allows us to calculate * the correct value for "nr", which means the zero-filled * part of the page is not copied back to userspace (unless * another truncate extends the file - this is desired though).
*/
isize = i_size_read(in->f_mapping->host); if (unlikely(*ppos >= isize)) break;
end_offset = min_t(loff_t, isize, *ppos + len);
/* * Once we start copying data, we don't want to be touching any * cachelines that might be contended:
*/
writably_mapped = mapping_writably_mapped(in->f_mapping);
for (i = 0; i < folio_batch_count(&fbatch); i++) { struct folio *folio = fbatch.folios[i];
size_t n;
if (folio_pos(folio) >= end_offset) goto out;
folio_mark_accessed(folio);
/* * If users can be writing to this folio using arbitrary * virtual addresses, take care of potential aliasing * before reading the folio on the kernel side.
*/ if (writably_mapped)
flush_dcache_folio(folio);
n = min_t(loff_t, len, isize - *ppos);
n = splice_folio_into_pipe(pipe, folio, *ppos, n); if (!n) goto out;
len -= n;
total_spliced += n;
*ppos += n;
in->f_ra.prev_pos = *ppos; if (pipe_is_full(pipe)) goto out;
}
/** * mapping_seek_hole_data - Seek for SEEK_DATA / SEEK_HOLE in the page cache. * @mapping: Address space to search. * @start: First byte to consider. * @end: Limit of search (exclusive). * @whence: Either SEEK_HOLE or SEEK_DATA. * * If the page cache knows which blocks contain holes and which blocks * contain data, your filesystem can use this function to implement * SEEK_HOLE and SEEK_DATA. This is useful for filesystems which are * entirely memory-based such as tmpfs, and filesystems which support * unwritten extents. * * Return: The requested offset on success, or -ENXIO if @whence specifies * SEEK_DATA and there is no data after @start. There is an implicit hole * after @end - 1, so SEEK_HOLE returns @end if all the bytes between @start * and @end contain data.
*/
loff_t mapping_seek_hole_data(struct address_space *mapping, loff_t start,
loff_t end, int whence)
{
XA_STATE(xas, &mapping->i_pages, start >> PAGE_SHIFT);
pgoff_t max = (end - 1) >> PAGE_SHIFT; bool seek_data = (whence == SEEK_DATA); struct folio *folio;
if (start < pos) { if (!seek_data) goto unlock;
start = pos;
}
seek_size = seek_folio_size(&xas, folio);
pos = round_up((u64)pos + 1, seek_size);
start = folio_seek_hole_data(&xas, mapping, folio, start, pos,
seek_data); if (start < pos) goto unlock; if (start >= end) break; if (seek_size > PAGE_SIZE)
xas_set(&xas, pos >> PAGE_SHIFT); if (!xa_is_value(folio))
folio_put(folio);
} if (seek_data)
start = -ENXIO;
unlock:
rcu_read_unlock(); if (folio && !xa_is_value(folio))
folio_put(folio); if (start > end) return end; return start;
}
#ifdef CONFIG_MMU #define MMAP_LOTSAMISS (100) /* * lock_folio_maybe_drop_mmap - lock the page, possibly dropping the mmap_lock * @vmf - the vm_fault for this fault. * @folio - the folio to lock. * @fpin - the pointer to the file we may pin (or is already pinned). * * This works similar to lock_folio_or_retry in that it can drop the * mmap_lock. It differs in that it actually returns the folio locked * if it returns 1 and 0 if it couldn't lock the folio. If we did have * to drop the mmap_lock then fpin will point to the pinned file and * needs to be fput()'ed at a later point.
*/ staticint lock_folio_maybe_drop_mmap(struct vm_fault *vmf, struct folio *folio, struct file **fpin)
{ if (folio_trylock(folio)) return 1;
/* * NOTE! This will make us return with VM_FAULT_RETRY, but with * the fault lock still held. That's how FAULT_FLAG_RETRY_NOWAIT * is supposed to work. We have way too many special cases..
*/ if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT) return 0;
*fpin = maybe_unlock_mmap_for_io(vmf, *fpin); if (vmf->flags & FAULT_FLAG_KILLABLE) { if (__folio_lock_killable(folio)) { /* * We didn't have the right flags to drop the * fault lock, but all fault_handlers only check * for fatal signals if we return VM_FAULT_RETRY, * so we need to drop the fault lock here and * return 0 if we don't have a fpin.
*/ if (*fpin == NULL)
release_fault_lock(vmf); return 0;
}
} else
__folio_lock(folio);
return 1;
}
/* * Synchronous readahead happens when we don't even find a page in the page * cache at all. We don't want to perform IO under the mmap sem, so if we have * to drop the mmap sem we return the file that was pinned in order for us to do * that. If we didn't pin a file then we return NULL. The file that is * returned needs to be fput()'ed when we're done with it.
*/ staticstruct file *do_sync_mmap_readahead(struct vm_fault *vmf)
{ struct file *file = vmf->vma->vm_file; struct file_ra_state *ra = &file->f_ra; struct address_space *mapping = file->f_mapping;
DEFINE_READAHEAD(ractl, file, ra, mapping, vmf->pgoff); struct file *fpin = NULL;
vm_flags_t vm_flags = vmf->vma->vm_flags; unsignedshort mmap_miss;
#ifdef CONFIG_TRANSPARENT_HUGEPAGE /* Use the readahead code, even if readahead is disabled */ if ((vm_flags & VM_HUGEPAGE) && HPAGE_PMD_ORDER <= MAX_PAGECACHE_ORDER) {
fpin = maybe_unlock_mmap_for_io(vmf, fpin);
ractl._index &= ~((unsignedlong)HPAGE_PMD_NR - 1);
ra->size = HPAGE_PMD_NR; /* * Fetch two PMD folios, so we get the chance to actually * readahead, unless we've been told not to.
*/ if (!(vm_flags & VM_RAND_READ))
ra->size *= 2;
ra->async_size = HPAGE_PMD_NR;
ra->order = HPAGE_PMD_ORDER;
page_cache_ra_order(&ractl, ra); return fpin;
} #endif
/* * If we don't want any read-ahead, don't bother. VM_EXEC case below is * already intended for random access.
*/ if ((vm_flags & (VM_RAND_READ | VM_EXEC)) == VM_RAND_READ) return fpin; if (!ra->ra_pages) return fpin;
/* Avoid banging the cache line if not needed */
mmap_miss = READ_ONCE(ra->mmap_miss); if (mmap_miss < MMAP_LOTSAMISS * 10)
WRITE_ONCE(ra->mmap_miss, ++mmap_miss);
/* * Do we miss much more than hit in this file? If so, * stop bothering with read-ahead. It will only hurt.
*/ if (mmap_miss > MMAP_LOTSAMISS) return fpin;
if (vm_flags & VM_EXEC) { /* * Allow arch to request a preferred minimum folio order for * executable memory. This can often be beneficial to * performance if (e.g.) arm64 can contpte-map the folio. * Executable memory rarely benefits from readahead, due to its * random access nature, so set async_size to 0. * * Limit to the boundaries of the VMA to avoid reading in any * pad that might exist between sections, which would be a waste * of memory.
*/ struct vm_area_struct *vma = vmf->vma; unsignedlong start = vma->vm_pgoff; unsignedlong end = start + vma_pages(vma); unsignedlong ra_end;
/* * Asynchronous readahead happens when we find the page and PG_readahead, * so we want to possibly extend the readahead further. We return the file that * was pinned if we have to drop the mmap_lock in order to do IO.
*/ staticstruct file *do_async_mmap_readahead(struct vm_fault *vmf, struct folio *folio)
{ struct file *file = vmf->vma->vm_file; struct file_ra_state *ra = &file->f_ra;
DEFINE_READAHEAD(ractl, file, ra, file->f_mapping, vmf->pgoff); struct file *fpin = NULL; unsignedshort mmap_miss;
/* If we don't want any read-ahead, don't bother */ if (vmf->vma->vm_flags & VM_RAND_READ || !ra->ra_pages) return fpin;
mmap_miss = READ_ONCE(ra->mmap_miss); if (mmap_miss)
WRITE_ONCE(ra->mmap_miss, --mmap_miss);
/* * We might have COW'ed a pagecache folio and might now have an mlocked * anon folio mapped. The original pagecache folio is not mlocked and * might have been evicted. During a read+clear/modify/write update of * the PTE, such as done in do_numa_page()/change_pte_range(), we * temporarily clear the PTE under PT lock and might detect it here as * "none" when not holding the PT lock. * * Not rechecking the PTE under PT lock could result in an unexpected * major fault in an mlock'ed region. Recheck only for this special * scenario while holding the PT lock, to not degrade non-mlocked * scenarios. Recheck the PTE without PT lock firstly, thereby reducing * the number of times we hold PT lock.
*/ if (!(vma->vm_flags & VM_LOCKED)) return 0;
if (!(vmf->flags & FAULT_FLAG_ORIG_PTE_VALID)) return 0;
ptep = pte_offset_map_ro_nolock(vma->vm_mm, vmf->pmd, vmf->address,
&vmf->ptl); if (unlikely(!ptep)) return VM_FAULT_NOPAGE;
if (unlikely(!pte_none(ptep_get_lockless(ptep)))) {
ret = VM_FAULT_NOPAGE;
} else {
spin_lock(vmf->ptl); if (unlikely(!pte_none(ptep_get(ptep))))
ret = VM_FAULT_NOPAGE;
spin_unlock(vmf->ptl);
}
pte_unmap(ptep); return ret;
}
/** * filemap_fault - read in file data for page fault handling * @vmf: struct vm_fault containing details of the fault * * filemap_fault() is invoked via the vma operations vector for a * mapped memory region to read in file data during a page fault. * * The goto's are kind of ugly, but this streamlines the normal case of having * it in the page cache, and handles the special cases reasonably without * having a lot of duplicated code. * * vma->vm_mm->mmap_lock must be held on entry. * * If our return value has VM_FAULT_RETRY set, it's because the mmap_lock * may be dropped before doing I/O or by lock_folio_maybe_drop_mmap(). * * If our return value does not have VM_FAULT_RETRY set, the mmap_lock * has not been released. * * We never return with VM_FAULT_RETRY and a bit from VM_FAULT_ERROR set. * * Return: bitwise-OR of %VM_FAULT_ codes.
*/
vm_fault_t filemap_fault(struct vm_fault *vmf)
{ int error; struct file *file = vmf->vma->vm_file; struct file *fpin = NULL; struct address_space *mapping = file->f_mapping; struct inode *inode = mapping->host;
pgoff_t max_idx, index = vmf->pgoff; struct folio *folio;
vm_fault_t ret = 0; bool mapping_locked = false;
max_idx = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); if (unlikely(index >= max_idx)) return VM_FAULT_SIGBUS;
trace_mm_filemap_fault(mapping, index);
/* * Do we have something in the page cache already?
*/
folio = filemap_get_folio(mapping, index); if (likely(!IS_ERR(folio))) { /* * We found the page, so try async readahead before waiting for * the lock.
*/ if (!(vmf->flags & FAULT_FLAG_TRIED))
fpin = do_async_mmap_readahead(vmf, folio); if (unlikely(!folio_test_uptodate(folio))) {
filemap_invalidate_lock_shared(mapping);
mapping_locked = true;
}
} else {
ret = filemap_fault_recheck_pte_none(vmf); if (unlikely(ret)) return ret;
/* No page in the page cache at all */
count_vm_event(PGMAJFAULT);
count_memcg_event_mm(vmf->vma->vm_mm, PGMAJFAULT);
ret = VM_FAULT_MAJOR;
fpin = do_sync_mmap_readahead(vmf);
retry_find: /* * See comment in filemap_create_folio() why we need * invalidate_lock
*/ if (!mapping_locked) {
filemap_invalidate_lock_shared(mapping);
mapping_locked = true;
}
folio = __filemap_get_folio(mapping, index,
FGP_CREAT|FGP_FOR_MMAP,
vmf->gfp_mask); if (IS_ERR(folio)) { if (fpin) goto out_retry;
filemap_invalidate_unlock_shared(mapping); return VM_FAULT_OOM;
}
}
if (!lock_folio_maybe_drop_mmap(vmf, folio, &fpin)) goto out_retry;
/* Did it get truncated? */ if (unlikely(folio->mapping != mapping)) {
folio_unlock(folio);
folio_put(folio); goto retry_find;
}
VM_BUG_ON_FOLIO(!folio_contains(folio, index), folio);
/* * We have a locked folio in the page cache, now we need to check * that it's up-to-date. If not, it is going to be due to an error, * or because readahead was otherwise unable to retrieve it.
*/ if (unlikely(!folio_test_uptodate(folio))) { /* * If the invalidate lock is not held, the folio was in cache * and uptodate and now it is not. Strange but possible since we * didn't hold the page lock all the time. Let's drop * everything, get the invalidate lock and try again.
*/ if (!mapping_locked) {
folio_unlock(folio);
folio_put(folio); goto retry_find;
}
/* * OK, the folio is really not uptodate. This can be because the * VMA has the VM_RAND_READ flag set, or because an error * arose. Let's read it in directly.
*/ goto page_not_uptodate;
}
/* * We've made it this far and we had to drop our mmap_lock, now is the * time to return to the upper layer and have it re-find the vma and * redo the fault.
*/ if (fpin) {
folio_unlock(folio); goto out_retry;
} if (mapping_locked)
filemap_invalidate_unlock_shared(mapping);
/* * Found the page and have a reference on it. * We must recheck i_size under page lock.
*/
max_idx = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); if (unlikely(index >= max_idx)) {
folio_unlock(folio);
folio_put(folio); return VM_FAULT_SIGBUS;
}
vmf->page = folio_file_page(folio, index); return ret | VM_FAULT_LOCKED;
page_not_uptodate: /* * Umm, take care of errors if the page isn't up-to-date. * Try to re-read it _once_. We do this synchronously, * because there really aren't any performance issues here * and we need to check for errors.
*/
fpin = maybe_unlock_mmap_for_io(vmf, fpin);
error = filemap_read_folio(file, mapping->a_ops->read_folio, folio); if (fpin) goto out_retry;
folio_put(folio);
if (!error || error == AOP_TRUNCATED_PAGE) goto retry_find;
filemap_invalidate_unlock_shared(mapping);
return VM_FAULT_SIGBUS;
out_retry: /* * We dropped the mmap_lock, we need to return to the fault handler to * re-find the vma and come back and find our hopefully still populated * page.
*/ if (!IS_ERR(folio))
folio_put(folio); if (mapping_locked)
filemap_invalidate_unlock_shared(mapping); if (fpin)
fput(fpin); return ret | VM_FAULT_RETRY;
}
EXPORT_SYMBOL(filemap_fault);
do { if (!folio) return NULL; if (xas_retry(xas, folio)) continue; if (xa_is_value(folio)) continue; if (!folio_try_get(folio)) continue; if (folio_test_locked(folio)) goto skip; /* Has the page moved or been split? */ if (unlikely(folio != xas_reload(xas))) goto skip; if (!folio_test_uptodate(folio) || folio_test_readahead(folio)) goto skip; if (!folio_trylock(folio)) goto skip; if (folio->mapping != mapping) goto unlock; if (!folio_test_uptodate(folio)) goto unlock;
max_idx = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); if (xas->xa_index >= max_idx) goto unlock; return folio;
unlock:
folio_unlock(folio);
skip:
folio_put(folio);
} while ((folio = xas_next_entry(xas, end_pgoff)) != NULL);
return NULL;
}
/* * Map page range [start_page, start_page + nr_pages) of folio. * start_page is gotten from start by folio_page(folio, start)
*/ static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf, struct folio *folio, unsignedlong start, unsignedlong addr, unsignedint nr_pages, unsignedlong *rss, unsignedshort *mmap_miss)
{
vm_fault_t ret = 0; struct page *page = folio_page(folio, start); unsignedint count = 0;
pte_t *old_ptep = vmf->pte;
do { if (PageHWPoison(page + count)) goto skip;
/* * If there are too many folios that are recently evicted * in a file, they will probably continue to be evicted. * In such situation, read-ahead is only a waste of IO. * Don't decrease mmap_miss in this scenario to make sure * we can stop read-ahead.
*/ if (!folio_test_workingset(folio))
(*mmap_miss)++;
/* * NOTE: If there're PTE markers, we'll leave them to be * handled in the specific fault path, and it'll prohibit the * fault-around logic.
*/ if (!pte_none(ptep_get(&vmf->pte[count]))) goto skip;
count++; continue;
skip: if (count) {
set_pte_range(vmf, folio, page, count, addr);
*rss += count;
folio_ref_add(folio, count); if (in_range(vmf->address, addr, count * PAGE_SIZE))
ret = VM_FAULT_NOPAGE;
}
/* See comment of filemap_map_folio_range() */ if (!folio_test_workingset(folio))
(*mmap_miss)++;
/* * NOTE: If there're PTE markers, we'll leave them to be * handled in the specific fault path, and it'll prohibit * the fault-around logic.
*/ if (!pte_none(ptep_get(vmf->pte))) return ret;
/* * Do not allow to map with PTEs beyond i_size and with PMD * across i_size to preserve SIGBUS semantics. * * Make an exception for shmem/tmpfs that for long time * intentionally mapped with PMDs across i_size.
*/
can_map_large = shmem_mapping(mapping) ||
file_end >= folio_next_index(folio);
if (can_map_large && filemap_map_pmd(vmf, folio, start_pgoff)) {
ret = VM_FAULT_NOPAGE; goto out;
}
sb_start_pagefault(mapping->host->i_sb);
file_update_time(vmf->vma->vm_file);
folio_lock(folio); if (folio->mapping != mapping) {
folio_unlock(folio);
ret = VM_FAULT_NOPAGE; goto out;
} /* * We mark the folio dirty already here so that when freeze is in * progress, we are guaranteed that writeback during freezing will * see the dirty folio and writeprotect it again.
*/
folio_mark_dirty(folio);
folio_wait_stable(folio);
out:
sb_end_pagefault(mapping->host->i_sb); return ret;
}
/* * This is for filesystems which do not implement ->writepage.
*/ int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
{ if (vma_is_shared_maywrite(vma)) return -EINVAL; return generic_file_mmap(file, vma);
}
if (!filler)
filler = mapping->a_ops->read_folio;
repeat:
folio = filemap_get_folio(mapping, index); if (IS_ERR(folio)) {
folio = filemap_alloc_folio(gfp,
mapping_min_folio_order(mapping)); if (!folio) return ERR_PTR(-ENOMEM);
index = mapping_align_index(mapping, index);
err = filemap_add_folio(mapping, folio, index, gfp); if (unlikely(err)) {
folio_put(folio); if (err == -EEXIST) goto repeat; /* Presumably ENOMEM for xarray node */ return ERR_PTR(err);
}
goto filler;
} if (folio_test_uptodate(folio)) goto out;
if (!folio_trylock(folio)) {
folio_put_wait_locked(folio, TASK_UNINTERRUPTIBLE); goto repeat;
}
/* Folio was truncated from mapping */ if (!folio->mapping) {
folio_unlock(folio);
folio_put(folio); goto repeat;
}
/* Someone else locked and filled the page in a very small window */ if (folio_test_uptodate(folio)) {
folio_unlock(folio); goto out;
}
filler:
err = filemap_read_folio(file, filler, folio); if (err) {
folio_put(folio); if (err == AOP_TRUNCATED_PAGE) goto repeat; return ERR_PTR(err);
}
out:
folio_mark_accessed(folio); return folio;
}
/** * read_cache_folio - Read into page cache, fill it if needed. * @mapping: The address_space to read from. * @index: The index to read. * @filler: Function to perform the read, or NULL to use aops->read_folio(). * @file: Passed to filler function, may be NULL if not required. * * Read one page into the page cache. If it succeeds, the folio returned * will contain @index, but it may not be the first page of the folio. * * If the filler function returns an error, it will be returned to the * caller. * * Context: May sleep. Expects mapping->invalidate_lock to be held. * Return: An uptodate folio on success, ERR_PTR() on failure.
*/ struct folio *read_cache_folio(struct address_space *mapping, pgoff_t index,
filler_t filler, struct file *file)
{ return do_read_cache_folio(mapping, index, filler, file,
mapping_gfp_mask(mapping));
}
EXPORT_SYMBOL(read_cache_folio);
/** * mapping_read_folio_gfp - Read into page cache, using specified allocation flags. * @mapping: The address_space for the folio. * @index: The index that the allocated folio will contain. * @gfp: The page allocator flags to use if allocating. * * This is the same as "read_cache_folio(mapping, index, NULL, NULL)", but with * any new memory allocations done using the specified allocation flags. * * The most likely error from this function is EIO, but ENOMEM is * possible and so is EINTR. If ->read_folio returns another error, * that will be returned to the caller. * * The function expects mapping->invalidate_lock to be already held. * * Return: Uptodate folio on success, ERR_PTR() on failure.
*/ struct folio *mapping_read_folio_gfp(struct address_space *mapping,
pgoff_t index, gfp_t gfp)
{ return do_read_cache_folio(mapping, index, NULL, NULL, gfp);
}
EXPORT_SYMBOL(mapping_read_folio_gfp);
/** * read_cache_page_gfp - read into page cache, using specified page allocation flags. * @mapping: the page's address_space * @index: the page index * @gfp: the page allocator flags to use if allocating * * This is the same as "read_mapping_page(mapping, index, NULL)", but with * any new page allocations done using the specified allocation flags. * * If the page does not get brought uptodate, return -EIO. * * The function expects mapping->invalidate_lock to be already held. * * Return: up to date page on success, ERR_PTR() on failure.
*/ struct page *read_cache_page_gfp(struct address_space *mapping,
pgoff_t index,
gfp_t gfp)
{ return do_read_cache_page(mapping, index, NULL, NULL, gfp);
}
EXPORT_SYMBOL(read_cache_page_gfp);
/* * Warn about a page cache invalidation failure during a direct I/O write.
*/ staticvoid dio_warn_stale_pagecache(struct file *filp)
{ static DEFINE_RATELIMIT_STATE(_rs, 86400 * HZ, DEFAULT_RATELIMIT_BURST); char pathname[128]; char *path;
errseq_set(&filp->f_mapping->wb_err, -EIO); if (__ratelimit(&_rs)) {
path = file_path(filp, pathname, sizeof(pathname)); if (IS_ERR(path))
path = "(unknown)";
pr_crit("Page cache invalidation failure on direct I/O. Possible data corruption due to collision with buffered I/O!\n");
pr_crit("File: %s PID: %d Comm: %.20s\n", path, current->pid,
current->comm);
}
}
/* * If a page can not be invalidated, return 0 to fall back * to buffered write.
*/
written = kiocb_invalidate_pages(iocb, write_len); if (written) { if (written == -EBUSY) return 0; return written;
}
written = mapping->a_ops->direct_IO(iocb, from);
/* * Finally, try again to invalidate clean pages which might have been * cached by non-direct readahead, or faulted in by get_user_pages() * if the source of the write was an mmap'ed region of the file * we're writing. Either one is a pretty crazy thing to do, * so we don't support it 100%. If this invalidation * fails, tough, the write still worked... * * Most of the time we do not need this since dio_complete() will do * the invalidation for us. However there are some file systems that * do not end up with dio_complete() being called, so let's not break * them by removing it completely. * * Noticeable example is a blkdev_direct_IO(). * * Skip invalidation for async writes or if mapping has no pages.
*/ if (written > 0) { struct inode *inode = mapping->host;
loff_t pos = iocb->ki_pos;
if (mapping_writably_mapped(mapping))
flush_dcache_folio(folio);
/* * Faults here on mmap()s can recurse into arbitrary * filesystem code. Lots of locks are held that can * deadlock. Use an atomic copy to avoid deadlocking * in page fault handling.
*/
copied = copy_folio_from_iter_atomic(folio, offset, bytes, i);
flush_dcache_folio(folio);
status = a_ops->write_end(iocb, mapping, pos, bytes, copied,
folio, fsdata); if (unlikely(status != copied)) {
iov_iter_revert(i, copied - max(status, 0L)); if (unlikely(status < 0)) break;
}
cond_resched();
if (unlikely(status == 0)) { /* * A short copy made ->write_end() reject the * thing entirely. Might be memory poisoning * halfway through, might be a race with munmap, * might be severe memory pressure.
*/ if (chunk > PAGE_SIZE)
chunk /= 2; if (copied) {
bytes = copied; goto retry;
}
/* * 'folio' is now unlocked and faults on it can be * handled. Ensure forward progress by trying to * fault it in now.
*/ if (fault_in_iov_iter_readable(i, bytes) == bytes) {
status = -EFAULT; break;
}
} else {
pos += status;
written += status;
}
} while (iov_iter_count(i));
/** * __generic_file_write_iter - write data to a file * @iocb: IO state structure (file, offset, etc.) * @from: iov_iter with data to write * * This function does all the work needed for actually writing data to a * file. It does all basic checks, removes SUID from the file, updates * modification times and calls proper subroutines depending on whether we * do direct IO or a standard buffered write. * * It expects i_rwsem to be grabbed unless we work on a block device or similar * object which does not need locking at all. * * This function does *not* take care of syncing data in case of O_SYNC write. * A caller has to handle it. This is mainly due to the fact that we want to * avoid syncing under i_rwsem. * * Return: * * number of bytes written, even for truncated writes * * negative error code if no data has been written at all
*/
ssize_t __generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
{ struct file *file = iocb->ki_filp; struct address_space *mapping = file->f_mapping; struct inode *inode = mapping->host;
ssize_t ret;
ret = file_remove_privs(file); if (ret) return ret;
ret = file_update_time(file); if (ret) return ret;
if (iocb->ki_flags & IOCB_DIRECT) {
ret = generic_file_direct_write(iocb, from); /* * If the write stopped short of completing, fall back to * buffered writes. Some filesystems do this for writes to * holes, for example. For DAX files, a buffered write will * not succeed (even if it did, DAX does not handle dirty * page-cache pages correctly).
*/ if (ret < 0 || !iov_iter_count(from) || IS_DAX(inode)) return ret; return direct_write_fallback(iocb, from, ret,
generic_perform_write(iocb, from));
}
/** * generic_file_write_iter - write data to a file * @iocb: IO state structure * @from: iov_iter with data to write * * This is a wrapper around __generic_file_write_iter() to be used by most * filesystems. It takes care of syncing the file in case of O_SYNC file * and acquires i_rwsem as needed. * Return: * * negative error code if no data has been written at all of * vfs_fsync_range() failed for a synchronous write * * number of bytes written, even for truncated writes
*/
ssize_t generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
{ struct file *file = iocb->ki_filp; struct inode *inode = file->f_mapping->host;
ssize_t ret;
inode_lock(inode);
ret = generic_write_checks(iocb, from); if (ret > 0)
ret = __generic_file_write_iter(iocb, from);
inode_unlock(inode);
if (ret > 0)
ret = generic_write_sync(iocb, ret); return ret;
}
EXPORT_SYMBOL(generic_file_write_iter);
/** * filemap_release_folio() - Release fs-specific metadata on a folio. * @folio: The folio which the kernel is trying to free. * @gfp: Memory allocation flags (and I/O mode). * * The address_space is trying to release any data attached to a folio * (presumably at folio->private). * * This will also be called if the private_2 flag is set on a page, * indicating that the folio has other metadata associated with it. * * The @gfp argument specifies whether I/O may be performed to release * this page (__GFP_IO), and whether the call may block * (__GFP_RECLAIM & __GFP_FS). * * Return: %true if the release was successful, otherwise %false.
*/ bool filemap_release_folio(struct folio *folio, gfp_t gfp)
{ struct address_space * const mapping = folio->mapping;
BUG_ON(!folio_test_locked(folio)); if (!folio_needs_release(folio)) returntrue; if (folio_test_writeback(folio)) returnfalse;
/** * filemap_invalidate_inode - Invalidate/forcibly write back a range of an inode's pagecache * @inode: The inode to flush * @flush: Set to write back rather than simply invalidate. * @start: First byte to in range. * @end: Last byte in range (inclusive), or LLONG_MAX for everything from start * onwards. * * Invalidate all the folios on an inode that contribute to the specified * range, possibly writing them back first. Whilst the operation is * undertaken, the invalidate lock is held to prevent new folios from being * installed.
*/ int filemap_invalidate_inode(struct inode *inode, bool flush,
loff_t start, loff_t end)
{ struct address_space *mapping = inode->i_mapping;
pgoff_t first = start >> PAGE_SHIFT;
pgoff_t last = end >> PAGE_SHIFT;
pgoff_t nr = end == LLONG_MAX ? ULONG_MAX : last - first + 1;
if (!mapping || !mapping->nrpages || end < start) goto out;
/* Prevent new folios from being added to the inode. */
filemap_invalidate_lock(mapping);
if (!mapping->nrpages) goto unlock;
unmap_mapping_pages(mapping, first, nr, false);
/* Write back the data if we're asked to. */ if (flush) { struct writeback_control wbc = {
.sync_mode = WB_SYNC_ALL,
.nr_to_write = LONG_MAX,
.range_start = start,
.range_end = end,
};
filemap_fdatawrite_wbc(mapping, &wbc);
}
/* Wait for writeback to complete on all folios and discard. */
invalidate_inode_pages2_range(mapping, start / PAGE_SIZE, end / PAGE_SIZE);
#ifdef CONFIG_CACHESTAT_SYSCALL /** * filemap_cachestat() - compute the page cache statistics of a mapping * @mapping: The mapping to compute the statistics for. * @first_index: The starting page cache index. * @last_index: The final page index (inclusive). * @cs: the cachestat struct to write the result to. * * This will query the page cache statistics of a mapping in the * page range of [first_index, last_index] (inclusive). The statistics * queried include: number of dirty pages, number of pages marked for * writeback, and the number of (recently) evicted pages.
*/ staticvoid filemap_cachestat(struct address_space *mapping,
pgoff_t first_index, pgoff_t last_index, struct cachestat *cs)
{
XA_STATE(xas, &mapping->i_pages, first_index); struct folio *folio;
/* * Don't deref the folio. It is not pinned, and might * get freed (and reused) underneath us. * * We *could* pin it, but that would be expensive for * what should be a fast and lightweight syscall. * * Instead, derive all information of interest from * the rcu-protected xarray.
*/
/* swapin error results in poisoned entry */ if (non_swap_entry(swp)) goto resched;
/* * Getting a swap entry from the shmem * inode means we beat * shmem_unuse(). rcu_read_lock() * ensures swapoff waits for us before * freeing the swapper space. However, * we can race with swapping and * invalidation, so there might not be * a shadow in the swapcache (yet).
*/
shadow = get_shadow_from_swap_cache(swp); if (!shadow) goto resched;
} #endif if (workingset_test_recent(shadow, true, &workingset, false))
cs->nr_recently_evicted += nr_pages;
goto resched;
}
/* page is in cache */
cs->nr_cache += nr_pages;
if (xas_get_mark(&xas, PAGECACHE_TAG_DIRTY))
cs->nr_dirty += nr_pages;
if (xas_get_mark(&xas, PAGECACHE_TAG_WRITEBACK))
cs->nr_writeback += nr_pages;
resched: if (need_resched()) {
xas_pause(&xas);
cond_resched_rcu();
}
}
rcu_read_unlock();
}
/* * See mincore: reveal pagecache information only for files * that the calling process has write access to, or could (if * tried) open for writing.
*/ staticinlinebool can_do_cachestat(struct file *f)
{ if (f->f_mode & FMODE_WRITE) returntrue; if (inode_owner_or_capable(file_mnt_idmap(f), file_inode(f))) returntrue; return file_permission(f, MAY_WRITE) == 0;
}
/* * The cachestat(2) system call. * * cachestat() returns the page cache statistics of a file in the * bytes range specified by `off` and `len`: number of cached pages, * number of dirty pages, number of pages marked for writeback, * number of evicted pages, and number of recently evicted pages. * * An evicted page is a page that is previously in the page cache * but has been evicted since. A page is recently evicted if its last * eviction was recent enough that its reentry to the cache would * indicate that it is actively being used by the system, and that * there is memory pressure on the system. * * `off` and `len` must be non-negative integers. If `len` > 0, * the queried range is [`off`, `off` + `len`]. If `len` == 0, * we will query in the range from `off` to the end of the file. * * The `flags` argument is unused for now, but is included for future * extensibility. User should pass 0 (i.e no flag specified). * * Currently, hugetlbfs is not supported. * * Because the status of a page can change after cachestat() checks it * but before it returns to the application, the returned values may * contain stale information. * * return values: * zero - success * -EFAULT - cstat or cstat_range points to an illegal address * -EINVAL - invalid flags * -EBADF - invalid file descriptor * -EOPNOTSUPP - file descriptor is of a hugetlbfs file
*/
SYSCALL_DEFINE4(cachestat, unsignedint, fd, struct cachestat_range __user *, cstat_range, struct cachestat __user *, cstat, unsignedint, flags)
{ CLASS(fd, f)(fd); struct address_space *mapping; struct cachestat_range csr; struct cachestat cs;
pgoff_t first_index, last_index;
if (fd_empty(f)) return -EBADF;
if (copy_from_user(&csr, cstat_range, sizeof(struct cachestat_range))) return -EFAULT;
/* hugetlbfs is not supported */ if (is_file_hugepages(fd_file(f))) return -EOPNOTSUPP;
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