mm/filemap: Add pageset_lock_killable()

This is like lock_page_killable() but for use by callers who
know they have a pageset.  Convert __lock_page_killable() to be
__pageset_lock_killable().  This saves one call to compound_head() per
contended call to lock_page_killable().

__pageset_lock_killable() is 19 bytes smaller than __lock_page_killable()
was.  filemap_fault() shrinks by 74 bytes and __lock_page_or_retry()
shrinks by 71 bytes.  That's a total of 164 bytes of text saved.

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>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: David Howells <dhowells@redhat.com>

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 197d3f3beff3a74a68843901f33fc117bc8207c0..89e3a94ca8a8b1c68cc7638621525727fce9ab63 100644 (file)
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -654,7 +654,7 @@ static inline bool wake_page_match(struct wait_page_queue *wait_page,
 }
 
 void __pageset_lock(struct pageset *pageset);
-extern int __lock_page_killable(struct page *page);
+int __pageset_lock_killable(struct pageset *pageset);
 extern int __lock_page_async(struct page *page, struct wait_page_queue *wait);
 extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
                                unsigned int flags);
@@ -694,6 +694,14 @@ static inline void lock_page(struct page *page)
                __pageset_lock(pageset);
 }
 
+static inline int pageset_lock_killable(struct pageset *pageset)
+{
+       might_sleep();
+       if (!pageset_trylock(pageset))
+               return __pageset_lock_killable(pageset);
+       return 0;
+}
+
 /*
  * lock_page_killable is like lock_page but can be interrupted by fatal
  * signals.  It returns 0 if it locked the page and -EINTR if it was
@@ -701,10 +709,7 @@ static inline void lock_page(struct page *page)
  */
 static inline int lock_page_killable(struct page *page)
 {
-       might_sleep();
-       if (!trylock_page(page))
-               return __lock_page_killable(page);
-       return 0;
+       return pageset_lock_killable(page_pageset(page));
 }
 
 /*

diff --git a/mm/filemap.c b/mm/filemap.c
index 82853067d258f8348713c7d888fda8ade46e5fb4..eb9667cdef8d188d11106951b1642a1410f1f07e 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1589,14 +1589,13 @@ void __pageset_lock(struct pageset *pageset)
 }
 EXPORT_SYMBOL(__pageset_lock);
 
-int __lock_page_killable(struct page *__page)
+int __pageset_lock_killable(struct pageset *pageset)
 {
-       struct page *page = compound_head(__page);
-       wait_queue_head_t *q = page_waitqueue(page);
-       return wait_on_page_bit_common(q, page, PG_locked, TASK_KILLABLE,
+       wait_queue_head_t *q = page_waitqueue(&pageset->page);
+       return wait_on_page_bit_common(q, &pageset->page, PG_locked, TASK_KILLABLE,
                                        EXCLUSIVE);
 }
-EXPORT_SYMBOL_GPL(__lock_page_killable);
+EXPORT_SYMBOL_GPL(__pageset_lock_killable);
 
 int __lock_page_async(struct page *page, struct wait_page_queue *wait)
 {
@@ -1638,6 +1637,8 @@ int __lock_page_async(struct page *page, struct wait_page_queue *wait)
 int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
                         unsigned int flags)
 {
+       struct pageset *pageset = page_pageset(page);
+
        if (fault_flag_allow_retry_first(flags)) {
                /*
                 * CAUTION! In this case, mmap_lock is not released
@@ -1656,13 +1657,13 @@ int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
        if (flags & FAULT_FLAG_KILLABLE) {
                int ret;
 
-               ret = __lock_page_killable(page);
+               ret = __pageset_lock_killable(pageset);
                if (ret) {
                        mmap_read_unlock(mm);
                        return 0;
                }
        } else {
-               __pageset_lock(page_pageset(page));
+               __pageset_lock(pageset);
        }
 
        return 1;
@@ -2851,7 +2852,7 @@ static int lock_page_maybe_drop_mmap(struct vm_fault *vmf, struct page *page,
 
        *fpin = maybe_unlock_mmap_for_io(vmf, *fpin);
        if (vmf->flags & FAULT_FLAG_KILLABLE) {
-               if (__lock_page_killable(&pageset->page)) {
+               if (__pageset_lock_killable(pageset)) {
                        /*
                         * We didn't have the right flags to drop the mmap_lock,
                         * but all fault_handlers only check for fatal signals