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mm/filemap: Add folio_lock_killable() 

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

__folio_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>
This commit is contained in:
Matthew Wilcox (Oracle) 2020-12-08 00:07:31 -05:00
parent 7c23c782d5
commit af7f29d9e1
2 changed files with 19 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
include/linux/pagemap.h
View File

@ -653,7 +653,7 @@ static inline bool wake_page_match(struct wait_page_queue *wait_page,
}
void __folio_lock(struct folio *folio);
extern int __lock_page_killable(struct page *page);
int __folio_lock_killable(struct folio *folio);
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);
@ -693,6 +693,14 @@ static inline void lock_page(struct page *page)
__folio_lock(folio);
}
static inline int folio_lock_killable(struct folio *folio)
{
might_sleep();
if (!folio_trylock(folio))
return __folio_lock_killable(folio);
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
@ -700,10 +708,7 @@ 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 folio_lock_killable(page_folio(page));
}
/*

17
mm/filemap.c
View File

@ -1644,14 +1644,13 @@ void __folio_lock(struct folio *folio)
}
EXPORT_SYMBOL(__folio_lock);
int __lock_page_killable(struct page *__page)
int __folio_lock_killable(struct folio *folio)
{
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(&folio->page);
return wait_on_page_bit_common(q, &folio->page, PG_locked, TASK_KILLABLE,
EXCLUSIVE);
}
EXPORT_SYMBOL_GPL(__lock_page_killable);
EXPORT_SYMBOL_GPL(__folio_lock_killable);
int __lock_page_async(struct page *page, struct wait_page_queue *wait)
{
@ -1693,6 +1692,8 @@ 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 folio *folio = page_folio(page);
if (fault_flag_allow_retry_first(flags)) {
/*
* CAUTION! In this case, mmap_lock is not released
@ -1711,13 +1712,13 @@ 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 = __folio_lock_killable(folio);
if (ret) {
mmap_read_unlock(mm);
return 0;
}
} else {
__folio_lock(page_folio(page));
__folio_lock(folio);
}
return 1;
@ -2929,7 +2930,7 @@ 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(&folio->page)) {
if (__folio_lock_killable(folio)) {
/*
* We didn't have the right flags to drop the mmap_lock,
* but all fault_handlers only check for fatal signals