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-rw-r--r--fs/btrfs/extent_io.c75
1 files changed, 58 insertions, 17 deletions
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index eade0432bd..87082f9732 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2734,16 +2734,34 @@ static int fiemap_process_hole(struct btrfs_inode *inode,
* it beyond i_size.
*/
while (cur_offset < end && cur_offset < i_size) {
+ struct extent_state *cached_state = NULL;
u64 delalloc_start;
u64 delalloc_end;
u64 prealloc_start;
+ u64 lockstart;
+ u64 lockend;
u64 prealloc_len = 0;
bool delalloc;
+ lockstart = round_down(cur_offset, inode->root->fs_info->sectorsize);
+ lockend = round_up(end, inode->root->fs_info->sectorsize);
+
+ /*
+ * We are only locking for the delalloc range because that's the
+ * only thing that can change here. With fiemap we have a lock
+ * on the inode, so no buffered or direct writes can happen.
+ *
+ * However mmaps and normal page writeback will cause this to
+ * change arbitrarily. We have to lock the extent lock here to
+ * make sure that nobody messes with the tree while we're doing
+ * btrfs_find_delalloc_in_range.
+ */
+ lock_extent(&inode->io_tree, lockstart, lockend, &cached_state);
delalloc = btrfs_find_delalloc_in_range(inode, cur_offset, end,
delalloc_cached_state,
&delalloc_start,
&delalloc_end);
+ unlock_extent(&inode->io_tree, lockstart, lockend, &cached_state);
if (!delalloc)
break;
@@ -2911,15 +2929,15 @@ int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo,
u64 start, u64 len)
{
const u64 ino = btrfs_ino(inode);
- struct extent_state *cached_state = NULL;
struct extent_state *delalloc_cached_state = NULL;
struct btrfs_path *path;
struct fiemap_cache cache = { 0 };
struct btrfs_backref_share_check_ctx *backref_ctx;
u64 last_extent_end;
u64 prev_extent_end;
- u64 lockstart;
- u64 lockend;
+ u64 range_start;
+ u64 range_end;
+ const u64 sectorsize = inode->root->fs_info->sectorsize;
bool stopped = false;
int ret;
@@ -2930,12 +2948,11 @@ int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo,
goto out;
}
- lockstart = round_down(start, inode->root->fs_info->sectorsize);
- lockend = round_up(start + len, inode->root->fs_info->sectorsize);
- prev_extent_end = lockstart;
+ range_start = round_down(start, sectorsize);
+ range_end = round_up(start + len, sectorsize);
+ prev_extent_end = range_start;
btrfs_inode_lock(inode, BTRFS_ILOCK_SHARED);
- lock_extent(&inode->io_tree, lockstart, lockend, &cached_state);
ret = fiemap_find_last_extent_offset(inode, path, &last_extent_end);
if (ret < 0)
@@ -2943,7 +2960,7 @@ int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo,
btrfs_release_path(path);
path->reada = READA_FORWARD;
- ret = fiemap_search_slot(inode, path, lockstart);
+ ret = fiemap_search_slot(inode, path, range_start);
if (ret < 0) {
goto out_unlock;
} else if (ret > 0) {
@@ -2955,7 +2972,7 @@ int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo,
goto check_eof_delalloc;
}
- while (prev_extent_end < lockend) {
+ while (prev_extent_end < range_end) {
struct extent_buffer *leaf = path->nodes[0];
struct btrfs_file_extent_item *ei;
struct btrfs_key key;
@@ -2978,19 +2995,19 @@ int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo,
* The first iteration can leave us at an extent item that ends
* before our range's start. Move to the next item.
*/
- if (extent_end <= lockstart)
+ if (extent_end <= range_start)
goto next_item;
backref_ctx->curr_leaf_bytenr = leaf->start;
/* We have in implicit hole (NO_HOLES feature enabled). */
if (prev_extent_end < key.offset) {
- const u64 range_end = min(key.offset, lockend) - 1;
+ const u64 hole_end = min(key.offset, range_end) - 1;
ret = fiemap_process_hole(inode, fieinfo, &cache,
&delalloc_cached_state,
backref_ctx, 0, 0, 0,
- prev_extent_end, range_end);
+ prev_extent_end, hole_end);
if (ret < 0) {
goto out_unlock;
} else if (ret > 0) {
@@ -3000,7 +3017,7 @@ int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo,
}
/* We've reached the end of the fiemap range, stop. */
- if (key.offset >= lockend) {
+ if (key.offset >= range_end) {
stopped = true;
break;
}
@@ -3094,29 +3111,41 @@ check_eof_delalloc:
btrfs_free_path(path);
path = NULL;
- if (!stopped && prev_extent_end < lockend) {
+ if (!stopped && prev_extent_end < range_end) {
ret = fiemap_process_hole(inode, fieinfo, &cache,
&delalloc_cached_state, backref_ctx,
- 0, 0, 0, prev_extent_end, lockend - 1);
+ 0, 0, 0, prev_extent_end, range_end - 1);
if (ret < 0)
goto out_unlock;
- prev_extent_end = lockend;
+ prev_extent_end = range_end;
}
if (cache.cached && cache.offset + cache.len >= last_extent_end) {
const u64 i_size = i_size_read(&inode->vfs_inode);
if (prev_extent_end < i_size) {
+ struct extent_state *cached_state = NULL;
u64 delalloc_start;
u64 delalloc_end;
+ u64 lockstart;
+ u64 lockend;
bool delalloc;
+ lockstart = round_down(prev_extent_end, sectorsize);
+ lockend = round_up(i_size, sectorsize);
+
+ /*
+ * See the comment in fiemap_process_hole as to why
+ * we're doing the locking here.
+ */
+ lock_extent(&inode->io_tree, lockstart, lockend, &cached_state);
delalloc = btrfs_find_delalloc_in_range(inode,
prev_extent_end,
i_size - 1,
&delalloc_cached_state,
&delalloc_start,
&delalloc_end);
+ unlock_extent(&inode->io_tree, lockstart, lockend, &cached_state);
if (!delalloc)
cache.flags |= FIEMAP_EXTENT_LAST;
} else {
@@ -3127,7 +3156,6 @@ check_eof_delalloc:
ret = emit_last_fiemap_cache(fieinfo, &cache);
out_unlock:
- unlock_extent(&inode->io_tree, lockstart, lockend, &cached_state);
btrfs_inode_unlock(inode, BTRFS_ILOCK_SHARED);
out:
free_extent_state(delalloc_cached_state);
@@ -4024,6 +4052,19 @@ int read_extent_buffer_pages(struct extent_buffer *eb, int wait, int mirror_num,
if (test_and_set_bit(EXTENT_BUFFER_READING, &eb->bflags))
goto done;
+ /*
+ * Between the initial test_bit(EXTENT_BUFFER_UPTODATE) and the above
+ * test_and_set_bit(EXTENT_BUFFER_READING), someone else could have
+ * started and finished reading the same eb. In this case, UPTODATE
+ * will now be set, and we shouldn't read it in again.
+ */
+ if (unlikely(test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags))) {
+ clear_bit(EXTENT_BUFFER_READING, &eb->bflags);
+ smp_mb__after_atomic();
+ wake_up_bit(&eb->bflags, EXTENT_BUFFER_READING);
+ return 0;
+ }
+
clear_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags);
eb->read_mirror = 0;
check_buffer_tree_ref(eb);
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-16 22:36:55 +0000