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btrfs: simplify metadata pages reading

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Metadata pages currently use __do_readpage to read metadata pages,
unfortunately this function is also used to deal with ordinary data
pages. This makes the metadata pages reading code to go through multiple
hoops in order to adhere to __do_readpage invariants. Most of these are
necessary for data pages which could be compressed. For metadata it's
enough to simply build a bio and submit it.

To this effect simply call submit_extent_page directly from
read_extent_buffer_pages which is the only callpath used to populate
extent_buffers with data. This in turn enables further cleanups.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Nikolay Borisov 2020-09-14 12:37:04 +03:00 committed by David Sterba
parent 2f1d3e4b93
commit 0420177c08
1 changed files with 10 additions and 11 deletions
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21
fs/btrfs/extent_io.c
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@ -5573,20 +5573,19 @@ int read_extent_buffer_pages(struct extent_buffer *eb, int wait, int mirror_num)
} }
ClearPageError(page); ClearPageError(page);
err = __extent_read_full_page(page, err = submit_extent_page(REQ_OP_READ | REQ_META, NULL,
btree_get_extent, &bio, page, page_offset(page), PAGE_SIZE, 0,
mirror_num, &bio_flags, &bio, end_bio_extent_readpage,
REQ_META); mirror_num, 0, 0, false);
if (err) { if (err) {
ret = err;
/* /*
* We use &bio in above __extent_read_full_page, * We failed to submit the bio so it's the
* so we ensure that if it returns error, the * caller's responsibility to perform cleanup
* current page fails to add itself to bio and * i.e unlock page/set error bit.
* it's been unlocked.
*
* We must dec io_pages by ourselves.
*/ */
ret = err;
SetPageError(page);
unlock_page(page);
atomic_dec(&eb->io_pages); atomic_dec(&eb->io_pages);
} }
} else { } else {