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authorJens Axboe <axboe@kernel.dk>2020-05-22 09:18:38 -0600
committerJens Axboe <axboe@kernel.dk>2020-06-21 20:44:25 -0600
commit1a0a7853b901c35a742b3bf176cf4701a5c5817c (patch)
tree57a6b2a9b92eb001d8d5854868a16a88f8171f8f /mm/filemap.c
parentdd3e6d5039de1cbff4e20e2b34390ff44cdb182f (diff)
downloadlinux-1a0a7853b901c35a742b3bf176cf4701a5c5817c.tar.bz2
mm: support async buffered reads in generic_file_buffered_read()
Use the async page locking infrastructure, if IOCB_WAITQ is set in the passed in iocb. The caller must expect an -EIOCBQUEUED return value, which means that IO is started but not done yet. This is similar to how O_DIRECT signals the same operation. Once the callback is received by the caller for IO completion, the caller must retry the operation. Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'mm/filemap.c')
-rw-r--r--mm/filemap.c38
1 files changed, 27 insertions, 11 deletions
diff --git a/mm/filemap.c b/mm/filemap.c
index e8aaf43bee9f..a5b1fa8f7ce4 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1210,6 +1210,14 @@ static int __wait_on_page_locked_async(struct page *page,
return ret;
}
+static int wait_on_page_locked_async(struct page *page,
+ struct wait_page_queue *wait)
+{
+ if (!PageLocked(page))
+ return 0;
+ return __wait_on_page_locked_async(compound_head(page), wait, false);
+}
+
/**
* put_and_wait_on_page_locked - Drop a reference and wait for it to be unlocked
* @page: The page to wait for.
@@ -2049,17 +2057,25 @@ find_page:
index, last_index - index);
}
if (!PageUptodate(page)) {
- if (iocb->ki_flags & IOCB_NOWAIT) {
- put_page(page);
- goto would_block;
- }
-
/*
* See comment in do_read_cache_page on why
* wait_on_page_locked is used to avoid unnecessarily
* serialisations and why it's safe.
*/
- error = wait_on_page_locked_killable(page);
+ if (iocb->ki_flags & IOCB_WAITQ) {
+ if (written) {
+ put_page(page);
+ goto out;
+ }
+ error = wait_on_page_locked_async(page,
+ iocb->ki_waitq);
+ } else {
+ if (iocb->ki_flags & IOCB_NOWAIT) {
+ put_page(page);
+ goto would_block;
+ }
+ error = wait_on_page_locked_killable(page);
+ }
if (unlikely(error))
goto readpage_error;
if (PageUptodate(page))
@@ -2147,7 +2163,10 @@ page_ok:
page_not_up_to_date:
/* Get exclusive access to the page ... */
- error = lock_page_killable(page);
+ if (iocb->ki_flags & IOCB_WAITQ)
+ error = lock_page_async(page, iocb->ki_waitq);
+ else
+ error = lock_page_killable(page);
if (unlikely(error))
goto readpage_error;
@@ -2190,10 +2209,7 @@ readpage:
}
if (!PageUptodate(page)) {
- if (iocb->ki_flags & IOCB_WAITQ)
- error = lock_page_async(page, iocb->ki_waitq);
- else
- error = lock_page_killable(page);
+ error = lock_page_killable(page);
if (unlikely(error))
goto readpage_error;
if (!PageUptodate(page)) {