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btrfs: atomically insert the new extent in btrfs_split_ordered_extent

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Currently there is a small race window in btrfs_split_ordered_extent,
where the reduced old extent can be looked up on the per-inode rbtree
or the per-root list while the newly split out one isn't visible yet.

Fix this by open coding btrfs_alloc_ordered_extent in
btrfs_split_ordered_extent, and holding the tree lock and
root->ordered_extent_lock over the entire tree and extent manipulation.

Note that this introduces new lock ordering because previously
ordered_extent_lock was never held over the tree lock.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Christoph Hellwig 2023-05-24 17:03:14 +02:00 committed by David Sterba
parent 53d9981ca2
commit 816f589b8d
1 changed files with 27 additions and 16 deletions
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43
fs/btrfs/ordered-data.c
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@ -1135,15 +1135,17 @@ bool btrfs_try_lock_ordered_range(struct btrfs_inode *inode, u64 start, u64 end,
struct btrfs_ordered_extent *btrfs_split_ordered_extent(
struct btrfs_ordered_extent *ordered, u64 len)
{
struct inode *inode = ordered->inode;
struct btrfs_ordered_inode_tree *tree = &BTRFS_I(inode)->ordered_tree;
struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
struct btrfs_inode *inode = BTRFS_I(ordered->inode);
struct btrfs_ordered_inode_tree *tree = &inode->ordered_tree;
struct btrfs_root *root = inode->root;
struct btrfs_fs_info *fs_info = root->fs_info;
u64 file_offset = ordered->file_offset;
u64 disk_bytenr = ordered->disk_bytenr;
unsigned long flags = ordered->flags & BTRFS_ORDERED_TYPE_FLAGS;
struct btrfs_ordered_extent *new;
struct rb_node *node;
trace_btrfs_ordered_extent_split(BTRFS_I(inode), ordered);
trace_btrfs_ordered_extent_split(inode, ordered);
ASSERT(!(flags & (1U << BTRFS_ORDERED_COMPRESSED)));
@ -1163,7 +1165,16 @@ struct btrfs_ordered_extent *btrfs_split_ordered_extent(
if (WARN_ON_ONCE(!list_empty(&ordered->list)))
return ERR_PTR(-EINVAL);
spin_lock_irq(&tree->lock);
new = alloc_ordered_extent(inode, file_offset, len, len, disk_bytenr,
len, 0, flags, ordered->compress_type);
if (IS_ERR(new))
return new;
/* One ref for the tree. */
refcount_inc(&new->refs);
spin_lock_irq(&root->ordered_extent_lock);
spin_lock(&tree->lock);
/* Remove from tree once */
node = &ordered->rb_node;
rb_erase(node, &tree->tree);
@ -1182,19 +1193,19 @@ struct btrfs_ordered_extent *btrfs_split_ordered_extent(
if (node)
btrfs_panic(fs_info, -EEXIST,
"zoned: inconsistency in ordered tree at offset %llu",
ordered->file_offset);
ordered->file_offset);
spin_unlock_irq(&tree->lock);
node = tree_insert(&tree->tree, new->file_offset, &new->rb_node);
if (node)
btrfs_panic(fs_info, -EEXIST,
"zoned: inconsistency in ordered tree at offset %llu",
new->file_offset);
spin_unlock(&tree->lock);
/*
* The splitting extent is already counted and will be added again in
* btrfs_alloc_ordered_extent(). Subtract len to avoid double counting.
*/
percpu_counter_add_batch(&fs_info->ordered_bytes, -len, fs_info->delalloc_batch);
return btrfs_alloc_ordered_extent(BTRFS_I(inode), file_offset, len, len,
disk_bytenr, len, 0, flags,
ordered->compress_type);
list_add_tail(&new->root_extent_list, &root->ordered_extents);
root->nr_ordered_extents++;
spin_unlock_irq(&root->ordered_extent_lock);
return new;
}
int __init ordered_data_init(void)