mpage: mpage_readpages() should submit IO as read-ahead

a_ops->readpages() is only ever used for read-ahead, yet we don't flag
the IO being submitted as such.  Fix that up.  Any file system that uses
mpage_readpages() as its ->readpages() implementation will now get this
right.

Since we're passing in whether the IO is read-ahead or not, we don't
need to pass in the 'gfp' separately, as it is dependent on the IO being
read-ahead.  Kill off that member.

Add some documentation notes on ->readpages() being purely for
read-ahead.

Link: http://lkml.kernel.org/r/20180621010725.17813-3-axboe@kernel.dk
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Chris Mason <clm@fb.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jens Axboe 2018-08-17 15:45:36 -07:00 committed by Linus Torvalds
parent 357c120652
commit 74c8164e1c
3 changed files with 28 additions and 10 deletions

View file

@ -344,6 +344,10 @@ struct address_space_operations {
/* Set a page dirty. Return true if this dirtied it */
int (*set_page_dirty)(struct page *page);
/*
* Reads in the requested pages. Unlike ->readpage(), this is
* PURELY used for read-ahead!.
*/
int (*readpages)(struct file *filp, struct address_space *mapping,
struct list_head *pages, unsigned nr_pages);