mm: improve cleanup when ->readpages doesn't process all pages

If ->readpages doesn't process all the pages, then it is best to act as
though they weren't requested so that a subsequent readahead can try
again.

So:

  - remove any 'ahead' pages from the page cache so they can be loaded
    with ->readahead() rather then multiple ->read()s

  - update the file_ra_state to reflect the reads that were actually
    submitted.

This allows ->readpages() to abort early due e.g.  to congestion, which
will then allow us to remove the inode_read_congested() test from
page_Cache_async_ra().

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: NeilBrown <[email protected]>
Cc: Anna Schumaker <[email protected]>
Cc: Chao Yu <[email protected]>
Cc: Darrick J. Wong <[email protected]>
Cc: Ilya Dryomov <[email protected]>
Cc: Jaegeuk Kim <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jeff Layton <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Lars Ellenberg <[email protected]>
Cc: Miklos Szeredi <[email protected]>
Cc: Paolo Valente <[email protected]>
Cc: Philipp Reisner <[email protected]>
Cc: Ryusuke Konishi <[email protected]>
Cc: Trond Myklebust <[email protected]>
Cc: Wu Fengguang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions