diff options
| author | Qu Wenruo <wqu@suse.com> | 2024-02-17 16:59:49 +1030 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2024-03-05 17:13:23 +0100 |
| commit | 8e7e9c672fd810a099dc2ac92a80e8e95cd5b0dc (patch) | |
| tree | 60a6f6d218ebc78fea0016aae795d72bffb40bbc /fs/btrfs/subpage.h | |
| parent | 621b9ff18c009ed6512df93b63fcf7dbac4cb4e0 (diff) | |
btrfs: subpage: make reader lock utilize bitmap
Currently btrfs_subpage utilizes its atomic member @reader to manage the
reader counter. However it is only utilized to prevent the page to be
released/unlocked when we still have reads underway.
In that use case, we don't really allow multiple readers on the same
subpage sector. So here we can introduce a new locked bitmap to
represent exactly which subpage range is locked for read.
In theory we can remove btrfs_subpage::reader as it's just the set bits
of the new locked bitmap. But unfortunately bitmap doesn't provide such
handy API yet, so we still keep the reader counter.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/subpage.h')
| -rw-r--r-- | fs/btrfs/subpage.h | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/fs/btrfs/subpage.h b/fs/btrfs/subpage.h index 97ba2c100b0b..b6dc013b0fdc 100644 --- a/fs/btrfs/subpage.h +++ b/fs/btrfs/subpage.h @@ -33,7 +33,7 @@ struct btrfs_subpage_info { unsigned int total_nr_bits; /* - * *_start indicates where the bitmap starts, the length is always + * *_offset indicates where the bitmap starts, the length is always * @bitmap_size, which is calculated from PAGE_SIZE / sectorsize. */ unsigned int uptodate_offset; @@ -41,6 +41,16 @@ struct btrfs_subpage_info { unsigned int writeback_offset; unsigned int ordered_offset; unsigned int checked_offset; + + /* + * For locked bitmaps, normally it's subpage representation for folio + * Locked flag, but metadata is different: + * + * - Metadata doesn't really lock the folio + * It's just to prevent page::private get cleared before the last + * end_page_read(). + */ + unsigned int locked_offset; }; /* |