/** * ext4_block_to_path - parse the block number into array of offsets * @inode: inode in question (we are only interested in its superblock) * @i_block: block number to be parsed * @offsets: array to store the offsets in * @boundary: set this non-zero if the referred-to block is likely to be * followed (on disk) by an indirect block. * * To store the locations of file's data ext4 uses a data structure common * for UNIX filesystems - tree of pointers anchored in the inode, with * data blocks at leaves and indirect blocks in intermediate nodes. * This function translates the block number into path in that tree - * return value is the path length and @offsets[n] is the offset of * pointer to (n+1)th node in the nth one. If @block is out of range * (negative or too large) warning is printed and zero returned. * * Note: function doesn't find node addresses, so no IO is needed. All * we need to know is the capacity of indirect blocks (taken from the * inode->i_sb).
*/
/* * Portability note: the last comparison (check that we fit into triple * indirect block) is spelled differently, because otherwise on an * architecture with 32-bit longs and 8Kb pages we might get into trouble * if our filesystem had 8Kb blocks. We might use long long, but that would * kill us on x86. Oh, well, at least the sign propagation does not matter - * i_block would have to be negative in the very beginning, so we would not * get there at all.
*/
staticint ext4_block_to_path(struct inode *inode,
ext4_lblk_t i_block,
ext4_lblk_t offsets[4], int *boundary)
{ int ptrs = EXT4_ADDR_PER_BLOCK(inode->i_sb); int ptrs_bits = EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb); constlong direct_blocks = EXT4_NDIR_BLOCKS,
indirect_blocks = ptrs,
double_blocks = (1 << (ptrs_bits * 2)); int n = 0; int final = 0;
/** * ext4_get_branch - read the chain of indirect blocks leading to data * @inode: inode in question * @depth: depth of the chain (1 - direct pointer, etc.) * @offsets: offsets of pointers in inode/indirect blocks * @chain: place to store the result * @err: here we store the error value * * Function fills the array of triples <key, p, bh> and returns %NULL * if everything went OK or the pointer to the last filled triple * (incomplete one) otherwise. Upon the return chain[i].key contains * the number of (i+1)-th block in the chain (as it is stored in memory, * i.e. little-endian 32-bit), chain[i].p contains the address of that * number (it points into struct inode for i==0 and into the bh->b_data * for i>0) and chain[i].bh points to the buffer_head of i-th indirect * block for i>0 and NULL for i==0. In other words, it holds the block * numbers of the chain, addresses they were taken from (and where we can * verify that chain did not change) and buffer_heads hosting these * numbers. * * Function stops when it stumbles upon zero pointer (absent block) * (pointer to last triple returned, *@err == 0) * or when it gets an IO error reading an indirect block * (ditto, *@err == -EIO) * or when it reads all @depth-1 indirect blocks successfully and finds * the whole chain, all way to the data (returns %NULL, *err == 0). * * Need to be called with * down_read(&EXT4_I(inode)->i_data_sem)
*/ static Indirect *ext4_get_branch(struct inode *inode, int depth,
ext4_lblk_t *offsets,
Indirect chain[4], int *err)
{ struct super_block *sb = inode->i_sb;
Indirect *p = chain; struct buffer_head *bh; unsignedint key; int ret = -EIO;
*err = 0; /* i_data is not going away, no lock needed */
add_chain(chain, NULL, EXT4_I(inode)->i_data + *offsets); if (!p->key) goto no_block; while (--depth) {
key = le32_to_cpu(p->key); if (key > ext4_blocks_count(EXT4_SB(sb)->s_es)) { /* the block was out of range */
ret = -EFSCORRUPTED; goto failure;
}
bh = sb_getblk(sb, key); if (unlikely(!bh)) {
ret = -ENOMEM; goto failure;
}
if (!bh_uptodate_or_lock(bh)) { if (ext4_read_bh(bh, 0, NULL, false) < 0) {
put_bh(bh); goto failure;
} /* validate block references */ if (ext4_check_indirect_blockref(inode, bh)) {
put_bh(bh); goto failure;
}
}
add_chain(++p, bh, (__le32 *)bh->b_data + *++offsets); /* Reader: end */ if (!p->key) goto no_block;
} return NULL;
failure:
*err = ret;
no_block: return p;
}
/** * ext4_find_near - find a place for allocation with sufficient locality * @inode: owner * @ind: descriptor of indirect block. * * This function returns the preferred place for block allocation. * It is used when heuristic for sequential allocation fails. * Rules are: * + if there is a block to the left of our position - allocate near it. * + if pointer will live in indirect block - allocate near that block. * + if pointer will live in inode - allocate in the same * cylinder group. * * In the latter case we colour the starting block by the callers PID to * prevent it from clashing with concurrent allocations for a different inode * in the same block group. The PID is used here so that functionally related * files will be close-by on-disk. * * Caller must make sure that @ind is valid and will stay that way.
*/ static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
{ struct ext4_inode_info *ei = EXT4_I(inode);
__le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
__le32 *p;
/* Try to find previous block */ for (p = ind->p - 1; p >= start; p--) { if (*p) return le32_to_cpu(*p);
}
/* No such thing, so let's try location of indirect block */ if (ind->bh) return ind->bh->b_blocknr;
/* * It is going to be referred to from the inode itself? OK, just put it * into the same cylinder group then.
*/ return ext4_inode_to_goal_block(inode);
}
/** * ext4_find_goal - find a preferred place for allocation. * @inode: owner * @block: block we want * @partial: pointer to the last triple within a chain * * Normally this function find the preferred place for block allocation, * returns it. * Because this is only used for non-extent files, we limit the block nr * to 32 bits.
*/ static ext4_fsblk_t ext4_find_goal(struct inode *inode, ext4_lblk_t block,
Indirect *partial)
{
ext4_fsblk_t goal;
/* * XXX need to get goal block from mballoc's data structures
*/
/** * ext4_blks_to_allocate - Look up the block map and count the number * of direct blocks need to be allocated for the given branch. * * @branch: chain of indirect blocks * @k: number of blocks need for indirect blocks * @blks: number of data blocks to be mapped. * @blocks_to_boundary: the offset in the indirect block * * return the total number of blocks to be allocate, including the * direct and indirect blocks.
*/ staticint ext4_blks_to_allocate(Indirect *branch, int k, unsignedint blks, int blocks_to_boundary)
{ unsignedint count = 0;
/* * Simple case, [t,d]Indirect block(s) has not allocated yet * then it's clear blocks on that path have not allocated
*/ if (k > 0) { /* right now we don't handle cross boundary allocation */ if (blks < blocks_to_boundary + 1)
count += blks; else
count += blocks_to_boundary + 1; return count;
}
/** * ext4_alloc_branch() - allocate and set up a chain of blocks * @handle: handle for this transaction * @ar: structure describing the allocation request * @indirect_blks: number of allocated indirect blocks * @offsets: offsets (in the blocks) to store the pointers to next. * @branch: place to store the chain in. * * This function allocates blocks, zeroes out all but the last one, * links them into chain and (if we are synchronous) writes them to disk. * In other words, it prepares a branch that can be spliced onto the * inode. It stores the information about that chain in the branch[], in * the same format as ext4_get_branch() would do. We are calling it after * we had read the existing part of chain and partial points to the last * triple of that (one with zero ->key). Upon the exit we have the same * picture as after the successful ext4_get_block(), except that in one * place chain is disconnected - *branch->p is still zero (we did not * set the last link), but branch->key contains the number that should * be placed into *branch->p to fill that gap. * * If allocation fails we free all blocks we've allocated (and forget * their buffer_heads) and return the error value the from failed * ext4_alloc_block() (normally -ENOSPC). Otherwise we set the chain * as described above and return 0.
*/ staticint ext4_alloc_branch(handle_t *handle, struct ext4_allocation_request *ar, int indirect_blks, ext4_lblk_t *offsets,
Indirect *branch)
{ struct buffer_head * bh;
ext4_fsblk_t b, new_blocks[4];
__le32 *p; int i, j, err, len = 1;
for (i = 0; i <= indirect_blks; i++) { if (i == indirect_blks) {
new_blocks[i] = ext4_mb_new_blocks(handle, ar, &err);
} else {
ar->goal = new_blocks[i] = ext4_new_meta_blocks(handle,
ar->inode, ar->goal,
ar->flags & EXT4_MB_DELALLOC_RESERVED,
NULL, &err); /* Simplify error cleanup... */
branch[i+1].bh = NULL;
} if (err) {
i--; goto failed;
}
branch[i].key = cpu_to_le32(new_blocks[i]); if (i == 0) continue;
BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
err = ext4_handle_dirty_metadata(handle, ar->inode, bh); if (err) goto failed;
} return 0;
failed: if (i == indirect_blks) { /* Free data blocks */
ext4_free_blocks(handle, ar->inode, NULL, new_blocks[i],
ar->len, 0);
i--;
} for (; i >= 0; i--) { /* * We want to ext4_forget() only freshly allocated indirect * blocks. Buffer for new_blocks[i] is at branch[i+1].bh * (buffer at branch[0].bh is indirect block / inode already * existing before ext4_alloc_branch() was called). Also * because blocks are freshly allocated, we don't need to * revoke them which is why we don't set * EXT4_FREE_BLOCKS_METADATA.
*/
ext4_free_blocks(handle, ar->inode, branch[i+1].bh,
new_blocks[i], 1,
branch[i+1].bh ? EXT4_FREE_BLOCKS_FORGET : 0);
} return err;
}
/** * ext4_splice_branch() - splice the allocated branch onto inode. * @handle: handle for this transaction * @ar: structure describing the allocation request * @where: location of missing link * @num: number of indirect blocks we are adding * * This function fills the missing link and does all housekeeping needed in * inode (->i_blocks, etc.). In case of success we end up with the full * chain to new block and return 0.
*/ staticint ext4_splice_branch(handle_t *handle, struct ext4_allocation_request *ar,
Indirect *where, int num)
{ int i; int err = 0;
ext4_fsblk_t current_block;
/* * If we're splicing into a [td]indirect block (as opposed to the * inode) then we need to get write access to the [td]indirect block * before the splice.
*/ if (where->bh) {
BUFFER_TRACE(where->bh, "get_write_access");
err = ext4_journal_get_write_access(handle, ar->inode->i_sb,
where->bh, EXT4_JTR_NONE); if (err) goto err_out;
} /* That's it */
*where->p = where->key;
/* * Update the host buffer_head or inode to point to more just allocated * direct blocks blocks
*/ if (num == 0 && ar->len > 1) {
current_block = le32_to_cpu(where->key) + 1; for (i = 1; i < ar->len; i++)
*(where->p + i) = cpu_to_le32(current_block++);
}
/* We are done with atomic stuff, now do the rest of housekeeping */ /* had we spliced it onto indirect block? */ if (where->bh) { /* * If we spliced it onto an indirect block, we haven't * altered the inode. Note however that if it is being spliced * onto an indirect block at the very end of the file (the * file is growing) then we *will* alter the inode to reflect * the new i_size. But that is not done here - it is done in * generic_commit_write->__mark_inode_dirty->ext4_dirty_inode.
*/
ext4_debug("splicing indirect only\n");
BUFFER_TRACE(where->bh, "call ext4_handle_dirty_metadata");
err = ext4_handle_dirty_metadata(handle, ar->inode, where->bh); if (err) goto err_out;
} else { /* * OK, we spliced it into the inode itself on a direct block.
*/
err = ext4_mark_inode_dirty(handle, ar->inode); if (unlikely(err)) goto err_out;
ext4_debug("splicing direct\n");
} return err;
err_out: for (i = 1; i <= num; i++) { /* * branch[i].bh is newly allocated, so there is no * need to revoke the block, which is why we don't * need to set EXT4_FREE_BLOCKS_METADATA.
*/
ext4_free_blocks(handle, ar->inode, where[i].bh, 0, 1,
EXT4_FREE_BLOCKS_FORGET);
}
ext4_free_blocks(handle, ar->inode, NULL, le32_to_cpu(where[num].key),
ar->len, 0);
return err;
}
/* * The ext4_ind_map_blocks() function handles non-extents inodes * (i.e., using the traditional indirect/double-indirect i_blocks * scheme) for ext4_map_blocks(). * * Allocation strategy is simple: if we have to allocate something, we will * have to go the whole way to leaf. So let's do it before attaching anything * to tree, set linkage between the newborn blocks, write them if sync is * required, recheck the path, free and repeat if check fails, otherwise * set the last missing link (that will protect us from any truncate-generated * removals - all blocks on the path are immune now) and possibly force the * write on the parent block. * That has a nice additional property: no special recovery from the failed * allocations is needed - we simply release blocks and do not touch anything * reachable from inode. * * `handle' can be NULL if create == 0. * * return > 0, # of blocks mapped or allocated. * return = 0, if plain lookup failed. * return < 0, error case. * * The ext4_ind_get_blocks() function should be called with * down_write(&EXT4_I(inode)->i_data_sem) if allocating filesystem * blocks (i.e., flags has EXT4_GET_BLOCKS_CREATE set) or * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system * blocks.
*/ int ext4_ind_map_blocks(handle_t *handle, struct inode *inode, struct ext4_map_blocks *map, int flags)
{ struct ext4_allocation_request ar; int err = -EIO;
ext4_lblk_t offsets[4];
Indirect chain[4];
Indirect *partial; int indirect_blks; int blocks_to_boundary = 0; int depth;
u64 count = 0;
ext4_fsblk_t first_block = 0;
/* Next simple case - plain lookup failed */ if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) { unsigned epb = inode->i_sb->s_blocksize / sizeof(u32); int i;
/* * Count number blocks in a subtree under 'partial'. At each * level we count number of complete empty subtrees beyond * current offset and then descend into the subtree only * partially beyond current offset.
*/
count = 0; for (i = partial - chain + 1; i < depth; i++)
count = count * epb + (epb - offsets[i] - 1);
count++; /* Fill in size of a hole we found */
map->m_pblk = 0;
map->m_len = umin(map->m_len, count); goto cleanup;
}
/* Failed read of indirect block */ if (err == -EIO) goto cleanup;
/* * Okay, we need to do block allocation.
*/ if (ext4_has_feature_bigalloc(inode->i_sb)) {
EXT4_ERROR_INODE(inode, "Can't allocate blocks for " "non-extent mapped inodes with bigalloc");
err = -EFSCORRUPTED; goto out;
}
/* Set up for the direct block allocation */
memset(&ar, 0, sizeof(ar));
ar.inode = inode;
ar.logical = map->m_lblk; if (S_ISREG(inode->i_mode))
ar.flags = EXT4_MB_HINT_DATA; if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
ar.flags |= EXT4_MB_DELALLOC_RESERVED; if (flags & EXT4_GET_BLOCKS_METADATA_NOFAIL)
ar.flags |= EXT4_MB_USE_RESERVED;
/* the number of blocks need to allocate for [d,t]indirect blocks */
indirect_blks = (chain + depth) - partial - 1;
/* * Next look up the indirect map to count the totoal number of * direct blocks to allocate for this branch.
*/
ar.len = ext4_blks_to_allocate(partial, indirect_blks,
map->m_len, blocks_to_boundary);
/* * Block out ext4_truncate while we alter the tree
*/
err = ext4_alloc_branch(handle, &ar, indirect_blks,
offsets + (partial - chain), partial);
/* * The ext4_splice_branch call will free and forget any buffers * on the new chain if there is a failure, but that risks using * up transaction credits, especially for bitmaps where the * credits cannot be returned. Can we handle this somehow? We * may need to return -EAGAIN upwards in the worst case. --sct
*/ if (!err)
err = ext4_splice_branch(handle, &ar, partial, indirect_blks); if (err) goto cleanup;
/* * Calculate number of indirect blocks touched by mapping @nrblocks logically * contiguous blocks
*/ int ext4_ind_trans_blocks(struct inode *inode, int nrblocks)
{ /* * With N contiguous data blocks, we need at most * N/EXT4_ADDR_PER_BLOCK(inode->i_sb) + 1 indirect blocks, * 2 dindirect blocks, and 1 tindirect block
*/ return DIV_ROUND_UP(nrblocks, EXT4_ADDR_PER_BLOCK(inode->i_sb)) + 4;
}
staticint ext4_ind_trunc_restart_fn(handle_t *handle, struct inode *inode, struct buffer_head *bh, int *dropped)
{ int err;
if (bh) {
BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
err = ext4_handle_dirty_metadata(handle, inode, bh); if (unlikely(err)) return err;
}
err = ext4_mark_inode_dirty(handle, inode); if (unlikely(err)) return err; /* * Drop i_data_sem to avoid deadlock with ext4_map_blocks. At this * moment, get_block can be called only for blocks inside i_size since * page cache has been already dropped and writes are blocked by * i_rwsem. So we can safely drop the i_data_sem here.
*/
BUG_ON(EXT4_JOURNAL(inode) == NULL);
ext4_discard_preallocations(inode);
up_write(&EXT4_I(inode)->i_data_sem);
*dropped = 1; return 0;
}
/* * Truncate transactions can be complex and absolutely huge. So we need to * be able to restart the transaction at a convenient checkpoint to make * sure we don't overflow the journal. * * Try to extend this transaction for the purposes of truncation. If * extend fails, we restart transaction.
*/ staticint ext4_ind_truncate_ensure_credits(handle_t *handle, struct inode *inode, struct buffer_head *bh, int revoke_creds)
{ int ret; int dropped = 0;
ret = ext4_journal_ensure_credits_fn(handle, EXT4_RESERVE_TRANS_BLOCKS,
ext4_blocks_for_truncate(inode), revoke_creds,
ext4_ind_trunc_restart_fn(handle, inode, bh, &dropped)); if (dropped)
down_write(&EXT4_I(inode)->i_data_sem); if (ret <= 0) return ret; if (bh) {
BUFFER_TRACE(bh, "retaking write access");
ret = ext4_journal_get_write_access(handle, inode->i_sb, bh,
EXT4_JTR_NONE); if (unlikely(ret)) return ret;
} return 0;
}
/* * Probably it should be a library function... search for first non-zero word * or memcmp with zero_page, whatever is better for particular architecture. * Linus?
*/ staticinlineint all_zeroes(__le32 *p, __le32 *q)
{ while (p < q) if (*p++) return 0; return 1;
}
/** * ext4_find_shared - find the indirect blocks for partial truncation. * @inode: inode in question * @depth: depth of the affected branch * @offsets: offsets of pointers in that branch (see ext4_block_to_path) * @chain: place to store the pointers to partial indirect blocks * @top: place to the (detached) top of branch * * This is a helper function used by ext4_truncate(). * * When we do truncate() we may have to clean the ends of several * indirect blocks but leave the blocks themselves alive. Block is * partially truncated if some data below the new i_size is referred * from it (and it is on the path to the first completely truncated * data block, indeed). We have to free the top of that path along * with everything to the right of the path. Since no allocation * past the truncation point is possible until ext4_truncate() * finishes, we may safely do the latter, but top of branch may * require special attention - pageout below the truncation point * might try to populate it. * * We atomically detach the top of branch from the tree, store the * block number of its root in *@top, pointers to buffer_heads of * partially truncated blocks - in @chain[].bh and pointers to * their last elements that should not be removed - in * @chain[].p. Return value is the pointer to last filled element * of @chain. * * The work left to caller to do the actual freeing of subtrees: * a) free the subtree starting from *@top * b) free the subtrees whose roots are stored in * (@chain[i].p+1 .. end of @chain[i].bh->b_data) * c) free the subtrees growing from the inode past the @chain[0].
* (no partially truncated stuff there). */
static Indirect *ext4_find_shared(struct inode *inode, int depth,
ext4_lblk_t offsets[4], Indirect chain[4],
__le32 *top)
{
Indirect *partial, *p; int k, err;
*top = 0; /* Make k index the deepest non-null offset + 1 */ for (k = depth; k > 1 && !offsets[k-1]; k--)
;
partial = ext4_get_branch(inode, k, offsets, chain, &err); /* Writer: pointers */ if (!partial)
partial = chain + k-1; /* * If the branch acquired continuation since we've looked at it - * fine, it should all survive and (new) top doesn't belong to us.
*/ if (!partial->key && *partial->p) /* Writer: end */ goto no_top; for (p = partial; (p > chain) && all_zeroes((__le32 *) p->bh->b_data, p->p); p--)
; /* * OK, we've found the last block that must survive. The rest of our * branch should be detached before unlocking. However, if that rest * of branch is all ours and does not grow immediately from the inode * it's easier to cheat and just decrement partial->p.
*/ if (p == chain + k - 1 && p > chain) {
p->p--;
} else {
*top = *p->p; /* Nope, don't do this in ext4. Must leave the tree intact */ #if 0
*p->p = 0; #endif
} /* Writer: end */
/* * Zero a number of block pointers in either an inode or an indirect block. * If we restart the transaction we must again get write access to the * indirect block for further modification. * * We release `count' blocks on disk, but (last - first) may be greater * than `count' because there can be holes in there. * * Return 0 on success, 1 on invalid block range * and < 0 on fatal error.
*/ staticint ext4_clear_blocks(handle_t *handle, struct inode *inode, struct buffer_head *bh,
ext4_fsblk_t block_to_free, unsignedlong count, __le32 *first,
__le32 *last)
{
__le32 *p; int flags = EXT4_FREE_BLOCKS_VALIDATED; int err;
/** * ext4_free_data - free a list of data blocks * @handle: handle for this transaction * @inode: inode we are dealing with * @this_bh: indirect buffer_head which contains *@first and *@last * @first: array of block numbers * @last: points immediately past the end of array * * We are freeing all blocks referred from that array (numbers are stored as * little-endian 32-bit) and updating @inode->i_blocks appropriately. * * We accumulate contiguous runs of blocks to free. Conveniently, if these * blocks are contiguous then releasing them at one time will only affect one * or two bitmap blocks (+ group descriptor(s) and superblock) and we won't * actually use a lot of journal space. * * @this_bh will be %NULL if @first and @last point into the inode's direct * block pointers.
*/ staticvoid ext4_free_data(handle_t *handle, struct inode *inode, struct buffer_head *this_bh,
__le32 *first, __le32 *last)
{
ext4_fsblk_t block_to_free = 0; /* Starting block # of a run */ unsignedlong count = 0; /* Number of blocks in the run */
__le32 *block_to_free_p = NULL; /* Pointer into inode/ind corresponding to
block_to_free */
ext4_fsblk_t nr; /* Current block # */
__le32 *p; /* Pointer into inode/ind
for current block */ int err = 0;
if (this_bh) { /* For indirect block */
BUFFER_TRACE(this_bh, "get_write_access");
err = ext4_journal_get_write_access(handle, inode->i_sb,
this_bh, EXT4_JTR_NONE); /* Important: if we can't update the indirect pointers
* to the blocks, we can't free them. */ if (err) return;
}
for (p = first; p < last; p++) {
nr = le32_to_cpu(*p); if (nr) { /* accumulate blocks to free if they're contiguous */ if (count == 0) {
block_to_free = nr;
block_to_free_p = p;
count = 1;
} elseif (nr == block_to_free + count) {
count++;
} else {
err = ext4_clear_blocks(handle, inode, this_bh,
block_to_free, count,
block_to_free_p, p); if (err) break;
block_to_free = nr;
block_to_free_p = p;
count = 1;
}
}
}
if (this_bh) {
BUFFER_TRACE(this_bh, "call ext4_handle_dirty_metadata");
/* * The buffer head should have an attached journal head at this * point. However, if the data is corrupted and an indirect * block pointed to itself, it would have been detached when * the block was cleared. Check for this instead of OOPSing.
*/ if ((EXT4_JOURNAL(inode) == NULL) || bh2jh(this_bh))
ext4_handle_dirty_metadata(handle, inode, this_bh); else
EXT4_ERROR_INODE(inode, "circular indirect block detected at " "block %llu",
(unsignedlonglong) this_bh->b_blocknr);
}
}
/** * ext4_free_branches - free an array of branches * @handle: JBD handle for this transaction * @inode: inode we are dealing with * @parent_bh: the buffer_head which contains *@first and *@last * @first: array of block numbers * @last: pointer immediately past the end of array * @depth: depth of the branches to free * * We are freeing all blocks referred from these branches (numbers are * stored as little-endian 32-bit) and updating @inode->i_blocks * appropriately.
*/ staticvoid ext4_free_branches(handle_t *handle, struct inode *inode, struct buffer_head *parent_bh,
__le32 *first, __le32 *last, int depth)
{
ext4_fsblk_t nr;
__le32 *p;
if (ext4_handle_is_aborted(handle)) return;
if (depth--) { struct buffer_head *bh; int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
p = last; while (--p >= first) {
nr = le32_to_cpu(*p); if (!nr) continue; /* A hole */
/* * Everything below this pointer has been * released. Now let this top-of-subtree go. * * We want the freeing of this indirect block to be * atomic in the journal with the updating of the * bitmap block which owns it. So make some room in * the journal. * * We zero the parent pointer *after* freeing its * pointee in the bitmaps, so if extend_transaction() * for some reason fails to put the bitmap changes and * the release into the same transaction, recovery * will merely complain about releasing a free block, * rather than leaking blocks.
*/ if (ext4_handle_is_aborted(handle)) return; if (ext4_ind_truncate_ensure_credits(handle, inode,
NULL,
ext4_free_metadata_revoke_credits(
inode->i_sb, 1)) < 0) return;
/* * The forget flag here is critical because if * we are journaling (and not doing data * journaling), we have to make sure a revoke * record is written to prevent the journal * replay from overwriting the (former) * indirect block if it gets reallocated as a * data block. This must happen in the same * transaction where the data blocks are * actually freed.
*/
ext4_free_blocks(handle, inode, NULL, nr, 1,
EXT4_FREE_BLOCKS_METADATA|
EXT4_FREE_BLOCKS_FORGET);
if (parent_bh) { /* * The block which we have just freed is * pointed to by an indirect block: journal it
*/
BUFFER_TRACE(parent_bh, "get_write_access"); if (!ext4_journal_get_write_access(handle,
inode->i_sb, parent_bh,
EXT4_JTR_NONE)) {
*p = 0;
BUFFER_TRACE(parent_bh, "call ext4_handle_dirty_metadata");
ext4_handle_dirty_metadata(handle,
inode,
parent_bh);
}
}
}
} else { /* We have reached the bottom of the tree. */
BUFFER_TRACE(parent_bh, "free data blocks");
ext4_free_data(handle, inode, parent_bh, first, last);
}
}
/* * The orphan list entry will now protect us from any crash which * occurs before the truncate completes, so it is now safe to propagate * the new, shorter inode size (held for now in i_size) into the * on-disk inode. We do this via i_disksize, which is the value which * ext4 *really* writes onto the disk inode.
*/
ei->i_disksize = inode->i_size;
if (last_block == max_block) { /* * It is unnecessary to free any data blocks if last_block is * equal to the indirect block limit.
*/ return;
} elseif (n == 1) { /* direct blocks */
ext4_free_data(handle, inode, NULL, i_data+offsets[0],
i_data + EXT4_NDIR_BLOCKS); goto do_indirects;
}
partial = ext4_find_shared(inode, n, offsets, chain, &nr); /* Kill the top of shared branch (not detached) */ if (nr) { if (partial == chain) { /* Shared branch grows from the inode */
ext4_free_branches(handle, inode, NULL,
&nr, &nr+1, (chain+n-1) - partial);
*partial->p = 0; /* * We mark the inode dirty prior to restart, * and prior to stop. No need for it here.
*/
} else { /* Shared branch grows from an indirect block */
BUFFER_TRACE(partial->bh, "get_write_access");
ext4_free_branches(handle, inode, partial->bh,
partial->p,
partial->p+1, (chain+n-1) - partial);
}
} /* Clear the ends of indirect blocks on the shared branch */ while (partial > chain) {
ext4_free_branches(handle, inode, partial->bh, partial->p + 1,
(__le32*)partial->bh->b_data+addr_per_block,
(chain+n-1) - partial);
BUFFER_TRACE(partial->bh, "call brelse");
brelse(partial->bh);
partial--;
}
do_indirects: /* Kill the remaining (whole) subtrees */ switch (offsets[0]) { default:
nr = i_data[EXT4_IND_BLOCK]; if (nr) {
ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1);
i_data[EXT4_IND_BLOCK] = 0;
}
fallthrough; case EXT4_IND_BLOCK:
nr = i_data[EXT4_DIND_BLOCK]; if (nr) {
ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2);
i_data[EXT4_DIND_BLOCK] = 0;
}
fallthrough; case EXT4_DIND_BLOCK:
nr = i_data[EXT4_TIND_BLOCK]; if (nr) {
ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3);
i_data[EXT4_TIND_BLOCK] = 0;
}
fallthrough; case EXT4_TIND_BLOCK:
;
}
}
/** * ext4_ind_remove_space - remove space from the range * @handle: JBD handle for this transaction * @inode: inode we are dealing with * @start: First block to remove * @end: One block after the last block to remove (exclusive) * * Free the blocks in the defined range (end is exclusive endpoint of * range). This is used by ext4_punch_hole().
*/ int ext4_ind_remove_space(handle_t *handle, struct inode *inode,
ext4_lblk_t start, ext4_lblk_t end)
{ struct ext4_inode_info *ei = EXT4_I(inode);
__le32 *i_data = ei->i_data; int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
ext4_lblk_t offsets[4], offsets2[4];
Indirect chain[4], chain2[4];
Indirect *partial, *partial2;
Indirect *p = NULL, *p2 = NULL;
ext4_lblk_t max_block;
__le32 nr = 0, nr2 = 0; int n = 0, n2 = 0; unsigned blocksize = inode->i_sb->s_blocksize;
max_block = (EXT4_SB(inode->i_sb)->s_bitmap_maxbytes + blocksize-1)
>> EXT4_BLOCK_SIZE_BITS(inode->i_sb); if (end >= max_block)
end = max_block; if ((start >= end) || (start > max_block)) return 0;
if ((n == 1) && (n == n2)) { /* We're punching only within direct block range */
ext4_free_data(handle, inode, NULL, i_data + offsets[0],
i_data + offsets2[0]); return 0;
} elseif (n2 > n) { /* * Start and end are on a different levels so we're going to * free partial block at start, and partial block at end of * the range. If there are some levels in between then * do_indirects label will take care of that.
*/
if (n == 1) { /* * Start is at the direct block level, free * everything to the end of the level.
*/
ext4_free_data(handle, inode, NULL, i_data + offsets[0],
i_data + EXT4_NDIR_BLOCKS); goto end_range;
}
partial = p = ext4_find_shared(inode, n, offsets, chain, &nr); if (nr) { if (partial == chain) { /* Shared branch grows from the inode */
ext4_free_branches(handle, inode, NULL,
&nr, &nr+1, (chain+n-1) - partial);
*partial->p = 0;
} else { /* Shared branch grows from an indirect block */
BUFFER_TRACE(partial->bh, "get_write_access");
ext4_free_branches(handle, inode, partial->bh,
partial->p,
partial->p+1, (chain+n-1) - partial);
}
}
/* * Clear the ends of indirect blocks on the shared branch * at the start of the range
*/ while (partial > chain) {
ext4_free_branches(handle, inode, partial->bh,
partial->p + 1,
(__le32 *)partial->bh->b_data+addr_per_block,
(chain+n-1) - partial);
partial--;
}
end_range:
partial2 = p2 = ext4_find_shared(inode, n2, offsets2, chain2, &nr2); if (nr2) { if (partial2 == chain2) { /* * Remember, end is exclusive so here we're at * the start of the next level we're not going * to free. Everything was covered by the start * of the range.
*/ goto do_indirects;
}
} else { /* * ext4_find_shared returns Indirect structure which * points to the last element which should not be * removed by truncate. But this is end of the range * in punch_hole so we need to point to the next element
*/
partial2->p++;
}
/* * Clear the ends of indirect blocks on the shared branch * at the end of the range
*/ while (partial2 > chain2) {
ext4_free_branches(handle, inode, partial2->bh,
(__le32 *)partial2->bh->b_data,
partial2->p,
(chain2+n2-1) - partial2);
partial2--;
} goto do_indirects;
}
/* Punch happened within the same level (n == n2) */
partial = p = ext4_find_shared(inode, n, offsets, chain, &nr);
partial2 = p2 = ext4_find_shared(inode, n2, offsets2, chain2, &nr2);
/* Free top, but only if partial2 isn't its subtree. */ if (nr) { int level = min(partial - chain, partial2 - chain2); int i; int subtree = 1;
for (i = 0; i <= level; i++) { if (offsets[i] != offsets2[i]) {
subtree = 0; break;
}
}
if (!subtree) { if (partial == chain) { /* Shared branch grows from the inode */
ext4_free_branches(handle, inode, NULL,
&nr, &nr+1,
(chain+n-1) - partial);
*partial->p = 0;
} else { /* Shared branch grows from an indirect block */
BUFFER_TRACE(partial->bh, "get_write_access");
ext4_free_branches(handle, inode, partial->bh,
partial->p,
partial->p+1,
(chain+n-1) - partial);
}
}
}
if (!nr2) { /* * ext4_find_shared returns Indirect structure which * points to the last element which should not be * removed by truncate. But this is end of the range * in punch_hole so we need to point to the next element
*/
partial2->p++;
}
while (partial > chain || partial2 > chain2) { int depth = (chain+n-1) - partial; int depth2 = (chain2+n2-1) - partial2;
if (partial > chain && partial2 > chain2 &&
partial->bh->b_blocknr == partial2->bh->b_blocknr) { /* * We've converged on the same block. Clear the range, * then we're done.
*/
ext4_free_branches(handle, inode, partial->bh,
partial->p + 1,
partial2->p,
(chain+n-1) - partial); goto cleanup;
}
/* * The start and end partial branches may not be at the same * level even though the punch happened within one level. So, we * give them a chance to arrive at the same level, then walk * them in step with each other until we converge on the same * block.
*/ if (partial > chain && depth <= depth2) {
ext4_free_branches(handle, inode, partial->bh,
partial->p + 1,
(__le32 *)partial->bh->b_data+addr_per_block,
(chain+n-1) - partial);
partial--;
} if (partial2 > chain2 && depth2 <= depth) {
ext4_free_branches(handle, inode, partial2->bh,
(__le32 *)partial2->bh->b_data,
partial2->p,
(chain2+n2-1) - partial2);
partial2--;
}
}
cleanup: while (p && p > chain) {
BUFFER_TRACE(p->bh, "call brelse");
brelse(p->bh);
p--;
} while (p2 && p2 > chain2) {
BUFFER_TRACE(p2->bh, "call brelse");
brelse(p2->bh);
p2--;
} return 0;
do_indirects: /* Kill the remaining (whole) subtrees */ switch (offsets[0]) { default: if (++n >= n2) break;
nr = i_data[EXT4_IND_BLOCK]; if (nr) {
ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1);
i_data[EXT4_IND_BLOCK] = 0;
}
fallthrough; case EXT4_IND_BLOCK: if (++n >= n2) break;
nr = i_data[EXT4_DIND_BLOCK]; if (nr) {
ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2);
i_data[EXT4_DIND_BLOCK] = 0;
}
fallthrough; case EXT4_DIND_BLOCK: if (++n >= n2) break;
nr = i_data[EXT4_TIND_BLOCK]; if (nr) {
ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3);
i_data[EXT4_TIND_BLOCK] = 0;
}
fallthrough; case EXT4_TIND_BLOCK:
;
} goto cleanup;
}
Messung V0.5
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nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit,
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