btrfs: Use ihold instead of igrab in cow_file_range_async
ihold is supposed to be used when the caller already has a reference to
the inode. In the case of cow_file_range_async this invariants holds,
since the 3 call chains leading to this function all take a reference:
btrfs_writepage <--- does igrab
extent_write_full_page
__extent_writepage
writepage_delalloc
btrfs_run_delalloc_range
cow_file_range_async
extent_write_cache_pages <--- does igrab
__extent_writepage (same callchain as above)
and
submit_compressed_extents <-- already called from async CoW submit path,
which would have done ihold.
extent_write_locked_range
__extent_writepage
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ add comment ]
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 3c11982..d548538 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1193,7 +1193,12 @@ static int cow_file_range_async(struct inode *inode, struct page *locked_page,
while (start < end) {
async_cow = kmalloc(sizeof(*async_cow), GFP_NOFS);
BUG_ON(!async_cow); /* -ENOMEM */
- async_cow->inode = igrab(inode);
+ /*
+ * igrab is called higher up in the call chain, take only the
+ * lightweight reference for the callback lifetime
+ */
+ ihold(inode);
+ async_cow->inode = inode;
async_cow->fs_info = fs_info;
async_cow->locked_page = locked_page;
async_cow->start = start;