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btrfs: set UNMAPPED bit early in btrfs_clone_extent_buffer() for subpage support 

For the incoming subpage support, UNMAPPED extent buffer will have
different behavior in btrfs_release_extent_buffer().

This means we need to set UNMAPPED bit early before calling
btrfs_release_extent_buffer().

Currently there is only one caller which relies on
btrfs_release_extent_buffer() in its error path while set UNMAPPED bit
late:
- btrfs_clone_extent_buffer()

Make it subpage compatible by setting the UNMAPPED bit early, since
we're here, also move the UPTODATE bit early.

There is another caller, __alloc_dummy_extent_buffer(), setting
UNMAPPED bit late, but that function clean up the allocated page
manually, thus no need for any modification.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2021-01-26 16:33:46 +08:00 committed by David Sterba
parent 6869b0a8be
commit 62c053fbb2
1 changed files with 7 additions and 2 deletions
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9
fs/btrfs/extent_io.c
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@ -5064,6 +5064,13 @@ struct extent_buffer *btrfs_clone_extent_buffer(const struct extent_buffer *src)
if (new == NULL)
return NULL;
/*
* Set UNMAPPED before calling btrfs_release_extent_buffer(), as
* btrfs_release_extent_buffer() have different behavior for
* UNMAPPED subpage extent buffer.
*/
set_bit(EXTENT_BUFFER_UNMAPPED, &new->bflags);
for (i = 0; i < num_pages; i++) {
p = alloc_page(GFP_NOFS);
if (!p) {
@ -5076,9 +5083,7 @@ struct extent_buffer *btrfs_clone_extent_buffer(const struct extent_buffer *src)
new->pages[i] = p;
copy_page(page_address(p), page_address(src->pages[i]));
}
set_bit(EXTENT_BUFFER_UPTODATE, &new->bflags);
set_bit(EXTENT_BUFFER_UNMAPPED, &new->bflags);
return new;
}