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writeback: factor folio_prepare_writeback() out of write_cache_pages()

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Reduce write_cache_pages() by about 30 lines; much of it is commentary,
but it all bundles nicely into an obvious function.

[hch@lst.de: rename should_writeback_folio to folio_prepare_writeback per Jan]
Link: https://lkml.kernel.org/r/20240215063649.2164017-8-hch@lst.de
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Dave Chinner <dchinner@redhat.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2024-02-15 07:36:42 +01:00 committed by Andrew Morton
parent f946e0d22e
commit b1793929b7
1 changed files with 34 additions and 27 deletions
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61
mm/page-writeback.c
View file

@ -2360,6 +2360,38 @@ void tag_pages_for_writeback(struct address_space *mapping,
}
EXPORT_SYMBOL(tag_pages_for_writeback);
static bool folio_prepare_writeback(struct address_space *mapping,
struct writeback_control *wbc, struct folio *folio)
{
/*
* Folio truncated or invalidated. We can freely skip it then,
* even for data integrity operations: the folio has disappeared
* concurrently, so there could be no real expectation of this
* data integrity operation even if there is now a new, dirty
* folio at the same pagecache index.
*/
if (unlikely(folio->mapping != mapping))
return false;
/*
* Did somebody else write it for us?
*/
if (!folio_test_dirty(folio))
return false;
if (folio_test_writeback(folio)) {
if (wbc->sync_mode == WB_SYNC_NONE)
return false;
folio_wait_writeback(folio);
}
BUG_ON(folio_test_writeback(folio));
if (!folio_clear_dirty_for_io(folio))
return false;
return true;
}
/**
* write_cache_pages - walk the list of dirty pages of the given address space and write all of them.
* @mapping: address space structure to write
@ -2430,38 +2462,13 @@ int write_cache_pages(struct address_space *mapping,
for (i = 0; i < nr_folios; i++) {
folio = fbatch.folios[i];
folio_lock(folio);
/*
* Page truncated or invalidated. We can freely skip it
* then, even for data integrity operations: the page
* has disappeared concurrently, so there could be no
* real expectation of this data integrity operation
* even if there is now a new, dirty page at the same
* pagecache address.
*/
if (unlikely(folio->mapping != mapping)) {
continue_unlock:
if (!folio_prepare_writeback(mapping, wbc, folio)) {
folio_unlock(folio);
continue;
}
if (!folio_test_dirty(folio)) {
/* someone wrote it for us */
goto continue_unlock;
}
if (folio_test_writeback(folio)) {
if (wbc->sync_mode != WB_SYNC_NONE)
folio_wait_writeback(folio);
else
goto continue_unlock;
}
BUG_ON(folio_test_writeback(folio));
if (!folio_clear_dirty_for_io(folio))
goto continue_unlock;
trace_wbc_writepage(wbc, inode_to_bdi(mapping->host));
error = writepage(folio, wbc, data);
wbc->nr_to_write -= folio_nr_pages(folio);