From: Mike Kravetz mike.kravetz@oracle.com
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/20230621212403.174710-1-mike.kravetz@oracle.com Fixes: 9425c591e06a ("page cache: fix page_cache_next/prev_miss off by one") Signed-off-by: Mike Kravetz mike.kravetz@oracle.com Reported-by: kernel test robot oliver.sang@intel.com Closes: https://lore.kernel.org/oe-lkp/202306211346.1e9ff03e-oliver.sang@intel.com Reviewed-by: Sidhartha Kumar sidhartha.kumar@oracle.com Cc: Ackerley Tng ackerleytng@google.com Cc: Erdem Aktas erdemaktas@google.com Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: Matthew Wilcox willy@infradead.org Cc: Muchun Song songmuchun@bytedance.com Cc: Vishal Annapurve vannapurve@google.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/filemap.c | 26 ++++++++++---------------- 1 file changed, 10 insertions(+), 16 deletions(-)
--- a/mm/filemap.c +++ b/mm/filemap.c @@ -1760,9 +1760,7 @@ bool __folio_lock_or_retry(struct folio * * 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 addr 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 addr 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);