linux-toradex.git/mm/readahead.c, branch v5.9-rc5

mm: use memalloc_nofs_save in readahead path

2020-06-02T17:59:07+00:00

Ensure that memory allocations in the readahead path do not attempt to
reclaim file-backed pages, which could lead to a deadlock.  It is
possible, though unlikely this is the root cause of a problem observed
by Cong Wang.

Reported-by: Cong Wang 
Suggested-by: Michal Hocko 
Signed-off-by: Matthew Wilcox (Oracle) 
Signed-off-by: Andrew Morton 
Reviewed-by: William Kucharski 
Cc: Chao Yu 
Cc: Christoph Hellwig 
Cc: Darrick J. Wong 
Cc: Dave Chinner 
Cc: Eric Biggers 
Cc: Gao Xiang 
Cc: Jaegeuk Kim 
Cc: John Hubbard 
Cc: Joseph Qi 
Cc: Junxiao Bi 
Cc: Zi Yan 
Cc: Johannes Thumshirn 
Cc: Miklos Szeredi 
Link: http://lkml.kernel.org/r/20200414150233.24495-16-willy@infradead.org
Signed-off-by: Linus Torvalds

mm: document why we don't set PageReadahead

2020-06-02T17:59:07+00:00

If the page is already in cache, we don't set PageReadahead on it.

Signed-off-by: Matthew Wilcox (Oracle) 
Signed-off-by: Andrew Morton 
Reviewed-by: Christoph Hellwig 
Reviewed-by: William Kucharski 
Cc: Chao Yu 
Cc: Cong Wang 
Cc: Darrick J. Wong 
Cc: Dave Chinner 
Cc: Eric Biggers 
Cc: Gao Xiang 
Cc: Jaegeuk Kim 
Cc: John Hubbard 
Cc: Joseph Qi 
Cc: Junxiao Bi 
Cc: Michal Hocko 
Cc: Zi Yan 
Cc: Johannes Thumshirn 
Cc: Miklos Szeredi 
Link: http://lkml.kernel.org/r/20200414150233.24495-15-willy@infradead.org
Signed-off-by: Linus Torvalds

mm: add page_cache_readahead_unbounded

2020-06-02T17:59:06+00:00

ext4 and f2fs have duplicated the guts of the readahead code so they can
read past i_size.  Instead, separate out the guts of the readahead code
so they can call it directly.

Signed-off-by: Matthew Wilcox (Oracle) 
Signed-off-by: Andrew Morton 
Tested-by: Eric Biggers 
Reviewed-by: Christoph Hellwig 
Reviewed-by: William Kucharski 
Reviewed-by: Eric Biggers 
Cc: Chao Yu 
Cc: Cong Wang 
Cc: Darrick J. Wong 
Cc: Dave Chinner 
Cc: Gao Xiang 
Cc: Jaegeuk Kim 
Cc: John Hubbard 
Cc: Joseph Qi 
Cc: Junxiao Bi 
Cc: Michal Hocko 
Cc: Zi Yan 
Cc: Johannes Thumshirn 
Cc: Miklos Szeredi 
Link: http://lkml.kernel.org/r/20200414150233.24495-14-willy@infradead.org
Signed-off-by: Linus Torvalds

mm: move end_index check out of readahead loop

2020-06-02T17:59:06+00:00

By reducing nr_to_read, we can eliminate this check from inside the loop.

Signed-off-by: Matthew Wilcox (Oracle) 
Signed-off-by: Andrew Morton 
Reviewed-by: John Hubbard 
Reviewed-by: William Kucharski 
Cc: Chao Yu 
Cc: Christoph Hellwig 
Cc: Cong Wang 
Cc: Darrick J. Wong 
Cc: Dave Chinner 
Cc: Eric Biggers 
Cc: Gao Xiang 
Cc: Jaegeuk Kim 
Cc: Joseph Qi 
Cc: Junxiao Bi 
Cc: Michal Hocko 
Cc: Zi Yan 
Cc: Johannes Thumshirn 
Cc: Miklos Szeredi 
Link: http://lkml.kernel.org/r/20200414150233.24495-13-willy@infradead.org
Signed-off-by: Linus Torvalds

mm: add readahead address space operation

2020-06-02T17:59:06+00:00

This replaces ->readpages with a saner interface:
 - Return void instead of an ignored error code.
 - Page cache is already populated with locked pages when ->readahead
   is called.
 - New arguments can be passed to the implementation without changing
   all the filesystems that use a common helper function like
   mpage_readahead().

Signed-off-by: Matthew Wilcox (Oracle) 
Signed-off-by: Andrew Morton 
Reviewed-by: John Hubbard 
Reviewed-by: Christoph Hellwig 
Reviewed-by: William Kucharski 
Cc: Chao Yu 
Cc: Cong Wang 
Cc: Darrick J. Wong 
Cc: Dave Chinner 
Cc: Eric Biggers 
Cc: Gao Xiang 
Cc: Jaegeuk Kim 
Cc: Joseph Qi 
Cc: Junxiao Bi 
Cc: Michal Hocko 
Cc: Zi Yan 
Cc: Johannes Thumshirn 
Cc: Miklos Szeredi 
Link: http://lkml.kernel.org/r/20200414150233.24495-12-willy@infradead.org
Signed-off-by: Linus Torvalds

mm: put readahead pages in cache earlier

2020-06-02T17:59:06+00:00

When populating the page cache for readahead, mappings that use
->readpages must populate the page cache themselves as the pages are
passed on a linked list which would normally be used for the page
cache's LRU.  For mappings that use ->readpage or the upcoming
->readahead method, we can put the pages into the page cache as soon as
they're allocated, which solves a race between readahead and direct IO.
It also lets us remove the gfp argument from read_pages().

Use the new readahead_page() API to implement the repeated calls to
->readpage(), just like most filesystems will.

Signed-off-by: Matthew Wilcox (Oracle) 
Signed-off-by: Andrew Morton 
Reviewed-by: Christoph Hellwig 
Reviewed-by: William Kucharski 
Cc: Chao Yu 
Cc: Cong Wang 
Cc: Darrick J. Wong 
Cc: Dave Chinner 
Cc: Eric Biggers 
Cc: Gao Xiang 
Cc: Jaegeuk Kim 
Cc: John Hubbard 
Cc: Joseph Qi 
Cc: Junxiao Bi 
Cc: Michal Hocko 
Cc: Zi Yan 
Cc: Johannes Thumshirn 
Cc: Miklos Szeredi 
Link: http://lkml.kernel.org/r/20200414150233.24495-11-willy@infradead.org
Signed-off-by: Linus Torvalds

mm: remove 'page_offset' from readahead loop

2020-06-02T17:59:06+00:00

Replace the page_offset variable with 'index + i'.

Signed-off-by: Matthew Wilcox (Oracle) 
Signed-off-by: Andrew Morton 
Reviewed-by: John Hubbard 
Reviewed-by: Christoph Hellwig 
Reviewed-by: William Kucharski 
Cc: Chao Yu 
Cc: Cong Wang 
Cc: Darrick J. Wong 
Cc: Dave Chinner 
Cc: Eric Biggers 
Cc: Gao Xiang 
Cc: Jaegeuk Kim 
Cc: Joseph Qi 
Cc: Junxiao Bi 
Cc: Michal Hocko 
Cc: Zi Yan 
Cc: Johannes Thumshirn 
Cc: Miklos Szeredi 
Link: http://lkml.kernel.org/r/20200414150233.24495-10-willy@infradead.org
Signed-off-by: Linus Torvalds

mm: rename readahead loop variable to 'i'

2020-06-02T17:59:06+00:00

Change the type of page_idx to unsigned long, and rename it -- it's just
a loop counter, not a page index.

Suggested-by: John Hubbard 
Signed-off-by: Matthew Wilcox (Oracle) 
Signed-off-by: Andrew Morton 
Reviewed-by: Dave Chinner 
Reviewed-by: William Kucharski 
Reviewed-by: Johannes Thumshirn 
Cc: Chao Yu 
Cc: Christoph Hellwig 
Cc: Cong Wang 
Cc: Darrick J. Wong 
Cc: Eric Biggers 
Cc: Gao Xiang 
Cc: Jaegeuk Kim 
Cc: Joseph Qi 
Cc: Junxiao Bi 
Cc: Michal Hocko 
Cc: Zi Yan 
Cc: Miklos Szeredi 
Link: http://lkml.kernel.org/r/20200414150233.24495-9-willy@infradead.org
Signed-off-by: Linus Torvalds

mm: rename various 'offset' parameters to 'index'

2020-06-02T17:59:06+00:00

The word 'offset' is used ambiguously to mean 'byte offset within a
page', 'byte offset from the start of the file' and 'page offset from
the start of the file'.

Use 'index' to mean 'page offset from the start of the file' throughout
the readahead code.

[ We should probably rename the 'pgoff_t' type to 'pgidx_t' too - Linus ]

Signed-off-by: Matthew Wilcox (Oracle) 
Signed-off-by: Andrew Morton 
Reviewed-by: Zi Yan 
Reviewed-by: William Kucharski 
Cc: Chao Yu 
Cc: Christoph Hellwig 
Cc: Cong Wang 
Cc: Darrick J. Wong 
Cc: Dave Chinner 
Cc: Eric Biggers 
Cc: Gao Xiang 
Cc: Jaegeuk Kim 
Cc: John Hubbard 
Cc: Joseph Qi 
Cc: Junxiao Bi 
Cc: Michal Hocko 
Cc: Johannes Thumshirn 
Cc: Miklos Szeredi 
Link: http://lkml.kernel.org/r/20200414150233.24495-8-willy@infradead.org
Signed-off-by: Linus Torvalds

mm: use readahead_control to pass arguments

2020-06-02T17:59:06+00:00

In this patch, only between __do_page_cache_readahead() and
read_pages(), but it will be extended in upcoming patches.  The
read_pages() function becomes aops centric, as this makes the most sense
by the end of the patchset.

Signed-off-by: Matthew Wilcox (Oracle) 
Signed-off-by: Andrew Morton 
Reviewed-by: John Hubbard 
Reviewed-by: Christoph Hellwig 
Reviewed-by: William Kucharski 
Reviewed-by: Johannes Thumshirn 
Cc: Chao Yu 
Cc: Cong Wang 
Cc: Darrick J. Wong 
Cc: Dave Chinner 
Cc: Eric Biggers 
Cc: Gao Xiang 
Cc: Jaegeuk Kim 
Cc: Joseph Qi 
Cc: Junxiao Bi 
Cc: Michal Hocko 
Cc: Zi Yan 
Cc: Miklos Szeredi 
Link: http://lkml.kernel.org/r/20200414150233.24495-7-willy@infradead.org
Signed-off-by: Linus Torvalds