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authorMatthew Wilcox (Oracle) <willy@infradead.org>2020-12-07 23:44:35 +0300
committerMatthew Wilcox (Oracle) <willy@infradead.org>2021-09-27 16:27:30 +0300
commit4e1364286d0a2dd384bceb6db6185b99c0e2c0bc (patch)
tree57e1d10680fc3900a884c40f94dcb308bf5d5123 /mm/filemap.c
parent2f52578f9c64d7d9a96ab81c243cc20804fabf2b (diff)
downloadlinux-4e1364286d0a2dd384bceb6db6185b99c0e2c0bc.tar.xz
mm/filemap: Add folio_unlock()
Convert unlock_page() to call folio_unlock(). By using a folio we avoid a call to compound_head(). This shortens the function from 39 bytes to 25 and removes 4 instructions on x86-64. Because we still have unlock_page(), it's a net increase of 16 bytes of text for the kernel as a whole, but any path that uses folio_unlock() will execute 4 fewer instructions. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Acked-by: Jeff Layton <jlayton@kernel.org> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: William Kucharski <william.kucharski@oracle.com> Reviewed-by: David Howells <dhowells@redhat.com> Acked-by: Mike Rapoport <rppt@linux.ibm.com> Acked-by: Vlastimil Babka <vbabka@suse.cz>
Diffstat (limited to 'mm/filemap.c')
-rw-r--r--mm/filemap.c29
1 files changed, 12 insertions, 17 deletions
diff --git a/mm/filemap.c b/mm/filemap.c
index 9fcc3d94cfcd..191d7d39e838 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1490,29 +1490,24 @@ static inline bool clear_bit_unlock_is_negative_byte(long nr, volatile void *mem
#endif
/**
- * unlock_page - unlock a locked page
- * @page: the page
+ * folio_unlock - Unlock a locked folio.
+ * @folio: The folio.
*
- * Unlocks the page and wakes up sleepers in wait_on_page_locked().
- * Also wakes sleepers in wait_on_page_writeback() because the wakeup
- * mechanism between PageLocked pages and PageWriteback pages is shared.
- * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
+ * Unlocks the folio and wakes up any thread sleeping on the page lock.
*
- * Note that this depends on PG_waiters being the sign bit in the byte
- * that contains PG_locked - thus the BUILD_BUG_ON(). That allows us to
- * clear the PG_locked bit and test PG_waiters at the same time fairly
- * portably (architectures that do LL/SC can test any bit, while x86 can
- * test the sign bit).
+ * Context: May be called from interrupt or process context. May not be
+ * called from NMI context.
*/
-void unlock_page(struct page *page)
+void folio_unlock(struct folio *folio)
{
+ /* Bit 7 allows x86 to check the byte's sign bit */
BUILD_BUG_ON(PG_waiters != 7);
- page = compound_head(page);
- VM_BUG_ON_PAGE(!PageLocked(page), page);
- if (clear_bit_unlock_is_negative_byte(PG_locked, &page->flags))
- wake_up_page_bit(page, PG_locked);
+ BUILD_BUG_ON(PG_locked > 7);
+ VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
+ if (clear_bit_unlock_is_negative_byte(PG_locked, folio_flags(folio, 0)))
+ wake_up_page_bit(&folio->page, PG_locked);
}
-EXPORT_SYMBOL(unlock_page);
+EXPORT_SYMBOL(folio_unlock);
/**
* end_page_private_2 - Clear PG_private_2 and release any waiters