diff options
| author | Jens Axboe <axboe@kernel.dk> | 2020-05-22 09:12:09 -0600 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2020-06-21 20:44:25 -0600 |
| commit | dd3e6d5039de1cbff4e20e2b34390ff44cdb182f (patch) | |
| tree | 459a91bf1f1bf0ef2c2346a8f405499d1248d8cf /include | |
| parent | c7510ab2cf5ccd997fe7f194edfe09cc511abf99 (diff) | |
| download | lwn-dd3e6d5039de1cbff4e20e2b34390ff44cdb182f.tar.gz lwn-dd3e6d5039de1cbff4e20e2b34390ff44cdb182f.zip | |
mm: add support for async page locking
Normally waiting for a page to become unlocked, or locking the page,
requires waiting for IO to complete. Add support for lock_page_async()
and wait_on_page_locked_async(), which are callback based instead. This
allows a caller to get notified when a page becomes unlocked, rather
than wait for it.
We add a new iocb field, ki_waitq, to pass in the necessary data for this
to happen. We can unionize this with ki_cookie, since that is only used
for polled IO. Polled IO can never co-exist with async callbacks, as it is
(by definition) polled completions. struct wait_page_key is made public,
and we define struct wait_page_async as the interface between the caller
and the core.
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/fs.h | 7 | ||||
| -rw-r--r-- | include/linux/pagemap.h | 17 |
2 files changed, 23 insertions, 1 deletions
diff --git a/include/linux/fs.h b/include/linux/fs.h index 3f881a892ea7..2a5cf6080e68 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -315,6 +315,8 @@ enum rw_hint { #define IOCB_SYNC (1 << 5) #define IOCB_WRITE (1 << 6) #define IOCB_NOWAIT (1 << 7) +/* iocb->ki_waitq is valid */ +#define IOCB_WAITQ (1 << 8) struct kiocb { struct file *ki_filp; @@ -328,7 +330,10 @@ struct kiocb { int ki_flags; u16 ki_hint; u16 ki_ioprio; /* See linux/ioprio.h */ - unsigned int ki_cookie; /* for ->iopoll */ + union { + unsigned int ki_cookie; /* for ->iopoll */ + struct wait_page_queue *ki_waitq; /* for async buffered IO */ + }; randomized_struct_fields_end }; diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 2f18221bb5c8..e053e1d9a4d7 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -535,6 +535,7 @@ static inline int wake_page_match(struct wait_page_queue *wait_page, extern void __lock_page(struct page *page); extern int __lock_page_killable(struct page *page); +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); extern void unlock_page(struct page *page); @@ -572,6 +573,22 @@ static inline int lock_page_killable(struct page *page) } /* + * lock_page_async - Lock the page, unless this would block. If the page + * is already locked, then queue a callback when the page becomes unlocked. + * This callback can then retry the operation. + * + * Returns 0 if the page is locked successfully, or -EIOCBQUEUED if the page + * was already locked and the callback defined in 'wait' was queued. + */ +static inline int lock_page_async(struct page *page, + struct wait_page_queue *wait) +{ + if (!trylock_page(page)) + return __lock_page_async(page, wait); + return 0; +} + +/* * lock_page_or_retry - Lock the page, unless this would block and the * caller indicated that it can handle a retry. * |