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btrfs: subpage: only call btrfs_alloc_subpage() when sectorsize is smaller than PAGE_SIZE

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There are two call sites of btrfs_alloc_subpage():

- btrfs_attach_subpage()
  We have ensured sectorsize is smaller than PAGE_SIZE

- alloc_extent_buffer()
  We call btrfs_alloc_subpage() unconditionally.

The alloc_extent_buffer() forces us to check the sectorsize size against
page size inside btrfs_alloc_subpage().

Since the function name, btrfs_alloc_subpage(), already indicates it
should only get called for subpage cases, do the check in
alloc_extent_buffer() and add an ASSERT() in btrfs_alloc_subpage().

Reviewed-by: Nikolay Borisov <nborisov@suse.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 2021-08-17 17:38:49 +08:00 committed by David Sterba
parent 9675ea8c9d
commit fdf250db89
2 changed files with 10 additions and 9 deletions
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16
fs/btrfs/extent_io.c
View File

@ -6137,13 +6137,15 @@ struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info,
* page, but it may change in the future for 16K page size
* support, so we still preallocate the memory in the loop.
*/
ret = btrfs_alloc_subpage(fs_info, &prealloc,
BTRFS_SUBPAGE_METADATA);
if (ret < 0) {
unlock_page(p);
put_page(p);
exists = ERR_PTR(ret);
goto free_eb;
if (fs_info->sectorsize < PAGE_SIZE) {
ret = btrfs_alloc_subpage(fs_info, &prealloc,
BTRFS_SUBPAGE_METADATA);
if (ret < 0) {
unlock_page(p);
put_page(p);
exists = ERR_PTR(ret);
goto free_eb;
}
}
spin_lock(&mapping->private_lock);

3
fs/btrfs/subpage.c
View File

@ -104,8 +104,7 @@ int btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info,
struct btrfs_subpage **ret,
enum btrfs_subpage_type type)
{
if (fs_info->sectorsize == PAGE_SIZE)
return 0;
ASSERT(fs_info->sectorsize < PAGE_SIZE);
*ret = kzalloc(sizeof(struct btrfs_subpage), GFP_NOFS);
if (!*ret)