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btrfs: attach private to dummy extent buffer pages 

There are locations where we allocate dummy extent buffers for temporary
usage, like in tree_mod_log_rewind() or get_old_root().

These dummy extent buffers will be handled by the same eb accessors, and
if they don't have page::private subpage eb accessors could fail.

To address such problems, make __alloc_dummy_extent_buffer() attach
page private for dummy extent buffers too.

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 16:33:51 +08:00 committed by David Sterba
parent 8ff8466d29
commit 09bc1f0fb8
1 changed files with 8 additions and 1 deletions
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9
fs/btrfs/extent_io.c
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@ -5185,9 +5185,14 @@ struct extent_buffer *__alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
num_pages = num_extent_pages(eb);
for (i = 0; i < num_pages; i++) {
int ret;
eb->pages[i] = alloc_page(GFP_NOFS);
if (!eb->pages[i])
goto err;
ret = attach_extent_buffer_page(eb, eb->pages[i], NULL);
if (ret < 0)
goto err;
}
set_extent_buffer_uptodate(eb);
btrfs_set_header_nritems(eb, 0);
@ -5195,8 +5200,10 @@ struct extent_buffer *__alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
return eb;
err:
for (; i > 0; i--)
for (; i > 0; i--) {
detach_extent_buffer_page(eb, eb->pages[i - 1]);
__free_page(eb->pages[i - 1]);
}
__free_extent_buffer(eb);
return NULL;
}