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btrfs: update num_extent_pages to support subpage sized extent buffer

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For subpage sized extent buffer, we have ensured no extent buffer will
cross page boundary, thus we would only need one page for any extent
buffer.

Update function num_extent_pages to handle such case.  Now
num_extent_pages() returns 1 for subpage sized extent buffer.

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 2020-12-02 14:48:03 +08:00 committed by David Sterba
parent 1aaac38c83
commit 4a3dc93843
1 changed files with 8 additions and 2 deletions
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10
fs/btrfs/extent_io.h
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@ -203,8 +203,14 @@ void btrfs_readahead_node_child(struct extent_buffer *node, int slot);
static inline int num_extent_pages(const struct extent_buffer *eb)
{
return (round_up(eb->start + eb->len, PAGE_SIZE) >> PAGE_SHIFT) -
(eb->start >> PAGE_SHIFT);
/*
* For sectorsize == PAGE_SIZE case, since nodesize is always aligned to
* sectorsize, it's just eb->len >> PAGE_SHIFT.
*
* For sectorsize < PAGE_SIZE case, we could have nodesize < PAGE_SIZE,
* thus have to ensure we get at least one page.
*/
return (eb->len >> PAGE_SHIFT) ?: 1;
}
static inline int extent_buffer_uptodate(const struct extent_buffer *eb)