diff options
| author | Chi Zhiling <chizhiling@kylinos.cn> | 2025-06-05 13:49:35 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-08-28 16:30:58 +0200 |
| commit | 72e849b5b16a48ac6dc6c09997ce38b90b0f7d86 (patch) | |
| tree | 632c36f7f4264ba8902de9cd490864842b8ab975 /mm/filemap.c | |
| parent | 617a8d148d929bc2b54618cdc4fe9b6ac912e500 (diff) | |
readahead: fix return value of page_cache_next_miss() when no hole is found
commit bbcaee20e03ecaeeecba32a703816a0d4502b6c4 upstream.
max_scan in page_cache_next_miss always decreases to zero when no hole is
found, causing the return value to be index + 0.
Fix this by preserving the max_scan value throughout the loop.
Jan said "From what I know and have seen in the past, wrong responses
from page_cache_next_miss() can lead to readahead window reduction and
thus reduced read speeds."
Link: https://lkml.kernel.org/r/20250605054935.2323451-1-chizhiling@163.com
Fixes: 901a269ff3d5 ("filemap: fix page_cache_next_miss() when no hole found")
Signed-off-by: Chi Zhiling <chizhiling@kylinos.cn>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm/filemap.c')
| -rw-r--r-- | mm/filemap.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/filemap.c b/mm/filemap.c index fa18e71f9c88..ec69fadf014c 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1750,8 +1750,9 @@ pgoff_t page_cache_next_miss(struct address_space *mapping, pgoff_t index, unsigned long max_scan) { XA_STATE(xas, &mapping->i_pages, index); + unsigned long nr = max_scan; - while (max_scan--) { + while (nr--) { void *entry = xas_next(&xas); if (!entry || xa_is_value(entry)) return xas.xa_index; |