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authorMatthew Wilcox (Oracle) <willy@infradead.org>2023-06-28 19:55:48 +0100
committerAndrew Morton <akpm@linux-foundation.org>2023-07-08 09:29:30 -0700
commit8344a3d44be3d18671e18c4ba23bb03dd21e14ad (patch)
treed7e0f804bcf56763da3324a659ccfde50bccc4b1 /mm
parent6dca4ac6fc91fd41ea4d6c4511838d37f4e0eab2 (diff)
writeback: account the number of pages written back
nr_to_write is a count of pages, so we need to decrease it by the number of pages in the folio we just wrote, not by 1. Most callers specify either LONG_MAX or 1, so are unaffected, but writeback_sb_inodes() might end up writing 512x as many pages as it asked for. Dave added: : XFS is the only filesystem this would affect, right? AFAIA, nothing : else enables large folios and uses writeback through : write_cache_pages() at this point... : : In which case, I'd be surprised if much difference, if any, gets : noticed by anyone. Link: https://lkml.kernel.org/r/20230628185548.981888-1-willy@infradead.org Fixes: 793917d997df ("mm/readahead: Add large folio readahead") Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Cc: Jan Kara <jack@suse.cz> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/page-writeback.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 1d17fb1ec863..d3f42009bb70 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2434,6 +2434,7 @@ int write_cache_pages(struct address_space *mapping,
for (i = 0; i < nr_folios; i++) {
struct folio *folio = fbatch.folios[i];
+ unsigned long nr;
done_index = folio->index;
@@ -2471,6 +2472,7 @@ continue_unlock:
trace_wbc_writepage(wbc, inode_to_bdi(mapping->host));
error = writepage(folio, wbc, data);
+ nr = folio_nr_pages(folio);
if (unlikely(error)) {
/*
* Handle errors according to the type of
@@ -2489,8 +2491,7 @@ continue_unlock:
error = 0;
} else if (wbc->sync_mode != WB_SYNC_ALL) {
ret = error;
- done_index = folio->index +
- folio_nr_pages(folio);
+ done_index = folio->index + nr;
done = 1;
break;
}
@@ -2504,7 +2505,8 @@ continue_unlock:
* keep going until we have written all the pages
* we tagged for writeback prior to entering this loop.
*/
- if (--wbc->nr_to_write <= 0 &&
+ wbc->nr_to_write -= nr;
+ if (wbc->nr_to_write <= 0 &&
wbc->sync_mode == WB_SYNC_NONE) {
done = 1;
break;