From: Mike Kravetz <[email protected]>
commit 16f8eb3eea9eb2a1568279d64ca4dc977e7aa538 upstream
This reverts commit 9425c591e06a9ab27a145ba655fb50532cf0bcc9
The reverted commit fixed up routines primarily used by readahead code
such that they could also be used by hugetlb. Unfortunately, this
caused a performance regression as pointed out by the Closes: tag.
The hugetlb code which uses page_cache_next_miss will be addressed in
a subsequent patch.
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 9425c591e06a ("page cache: fix page_cache_next/prev_miss off by one")
Signed-off-by: Mike Kravetz <[email protected]>
Reported-by: kernel test robot <[email protected]>
Closes: https://lore.kernel.org/oe-lkp/[email protected]
Reviewed-by: Sidhartha Kumar <[email protected]>
Cc: [email protected]
Cc: Thomas Backlund <[email protected]>
Cc: Ackerley Tng <[email protected]>
Cc: Erdem Aktas <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Vishal Annapurve <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---
As pointed out in [1], this patch was missed in the 6.4 stable tree.
Resending this patch with a Cc: stable.
[1]: https://lore.kernel.org/all/[email protected]/T/#m9e33a9ccb76e4db123279b371cff57d4e1a1ed3a
mm/filemap.c | 26 ++++++++++----------------
1 file changed, 10 insertions(+), 16 deletions(-)
diff --git a/mm/filemap.c b/mm/filemap.c
index 8abce63b259c9..a2006936a6ae2 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1760,9 +1760,7 @@ bool __folio_lock_or_retry(struct folio *folio, struct mm_struct *mm,
*
* Return: The index of the gap if found, otherwise an index outside the
* range specified (in which case 'return - index >= max_scan' will be true).
- * In the rare case of index wrap-around, 0 will be returned. 0 will also
- * be returned if index == 0 and there is a gap at the index. We can not
- * wrap-around if passed index == 0.
+ * In the rare case of index wrap-around, 0 will be returned.
*/
pgoff_t page_cache_next_miss(struct address_space *mapping,
pgoff_t index, unsigned long max_scan)
@@ -1772,13 +1770,12 @@ pgoff_t page_cache_next_miss(struct address_space *mapping,
while (max_scan--) {
void *entry = xas_next(&xas);
if (!entry || xa_is_value(entry))
- return xas.xa_index;
- if (xas.xa_index == 0 && index != 0)
- return xas.xa_index;
+ break;
+ if (xas.xa_index == 0)
+ break;
}
- /* No gaps in range and no wrap-around, return index beyond range */
- return xas.xa_index + 1;
+ return xas.xa_index;
}
EXPORT_SYMBOL(page_cache_next_miss);
@@ -1799,9 +1796,7 @@ EXPORT_SYMBOL(page_cache_next_miss);
*
* Return: The index of the gap if found, otherwise an index outside the
* range specified (in which case 'index - return >= max_scan' will be true).
- * In the rare case of wrap-around, ULONG_MAX will be returned. ULONG_MAX
- * will also be returned if index == ULONG_MAX and there is a gap at the
- * index. We can not wrap-around if passed index == ULONG_MAX.
+ * In the rare case of wrap-around, ULONG_MAX will be returned.
*/
pgoff_t page_cache_prev_miss(struct address_space *mapping,
pgoff_t index, unsigned long max_scan)
@@ -1811,13 +1806,12 @@ pgoff_t page_cache_prev_miss(struct address_space *mapping,
while (max_scan--) {
void *entry = xas_prev(&xas);
if (!entry || xa_is_value(entry))
- return xas.xa_index;
- if (xas.xa_index == ULONG_MAX && index != ULONG_MAX)
- return xas.xa_index;
+ break;
+ if (xas.xa_index == ULONG_MAX)
+ break;
}
- /* No gaps in range and no wrap-around, return index beyond range */
- return xas.xa_index - 1;
+ return xas.xa_index;
}
EXPORT_SYMBOL(page_cache_prev_miss);
--
2.41.0