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Revert "page cache: fix page_cache_next/prev_miss off by one"

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This reverts commit 9425c591e0

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: 9425c591e0 ("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>
This commit is contained in:
Mike Kravetz 2023-06-21 14:24:02 -07:00 committed by Andrew Morton
parent 1bc545bff4
commit 16f8eb3eea
1 changed files with 10 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
mm/filemap.c
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@ -1728,9 +1728,7 @@ 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)
@ -1740,13 +1738,12 @@ 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);
@ -1767,9 +1764,7 @@ 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)
@ -1779,13 +1774,12 @@ 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);