linux.git/mm/readahead.c, branch v6.12

Merge tag 'pull-stable-struct_fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2024-09-23T16:35:36+00:00

Pull 'struct fd' updates from Al Viro:
 "Just the 'struct fd' layout change, with conversion to accessor
  helpers"

* tag 'pull-stable-struct_fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  add struct fd constructors, get rid of __to_fd()
  struct fd: representation change
  introduce fd_file(), convert all accessors to it.

readahead: allocate folios with mapping_min_order in readahead

2024-08-23T11:49:48+00:00

page_cache_ra_unbounded() was allocating single pages (0 order folios)
if there was no folio found in an index. Allocate mapping_min_order folios
as we need to guarantee the minimum order if it is set.

page_cache_ra_order() tries to allocate folio to the page cache with a
higher order if the index aligns with that order. Modify it so that the
order does not go below the mapping_min_order requirement of the page
cache. This function will do the right thing even if the new_order passed
is less than the mapping_min_order.
When adding new folios to the page cache we must also ensure the index
used is aligned to the mapping_min_order as the page cache requires the
index to be aligned to the order of the folio.

readahead_expand() is called from readahead aops to extend the range of
the readahead so this function can assume ractl->_index to be aligned with
min_order.

Signed-off-by: Pankaj Raghav 
Co-developed-by: Hannes Reinecke 
Signed-off-by: Hannes Reinecke 
Link: https://lore.kernel.org/r/20240822135018.1931258-4-kernel@pankajraghav.com
Tested-by: David Howells 
Acked-by: Darrick J. Wong 
Reviewed-by: Darrick J. Wong 
Reviewed-by: Daniel Gomez 
Reviewed-by: Dave Chinner 
Reviewed-by: Hannes Reinecke 
Signed-off-by: Christian Brauner

fs: Allow fine-grained control of folio sizes

2024-08-23T11:49:48+00:00

We need filesystems to be able to communicate acceptable folio sizes
to the pagecache for a variety of uses (e.g. large block sizes).
Support a range of folio sizes between order-0 and order-31.

Signed-off-by: Matthew Wilcox (Oracle) 
Co-developed-by: Pankaj Raghav 
Signed-off-by: Pankaj Raghav 
Link: https://lore.kernel.org/r/20240822135018.1931258-2-kernel@pankajraghav.com
Tested-by: David Howells 
Reviewed-by: Hannes Reinecke 
Reviewed-by: Darrick J. Wong 
Reviewed-by: Daniel Gomez 
Signed-off-by: Christian Brauner

introduce fd_file(), convert all accessors to it.

2024-08-13T02:00:43+00:00

	For any changes of struct fd representation we need to
turn existing accesses to fields into calls of wrappers.
Accesses to struct fd::flags are very few (3 in linux/file.h,
1 in net/socket.c, 3 in fs/overlayfs/file.c and 3 more in
explicit initializers).
	Those can be dealt with in the commit converting to
new layout; accesses to struct fd::file are too many for that.
	This commit converts (almost) all of f.file to
fd_file(f).  It's not entirely mechanical ('file' is used as
a member name more than just in struct fd) and it does not
even attempt to distinguish the uses in pointer context from
those in boolean context; the latter will be eventually turned
into a separate helper (fd_empty()).

	NOTE: mass conversion to fd_empty(), tempting as it
might be, is a bad idea; better do that piecewise in commit
that convert from fdget...() to CLASS(...).

[conflicts in fs/fhandle.c, kernel/bpf/syscall.c, mm/memcontrol.c
caught by git; fs/stat.c one got caught by git grep]
[fs/xattr.c conflict]

Reviewed-by: Christian Brauner 
Signed-off-by: Al Viro

Merge branch 'mm-hotfixes-stable' into mm-stable to pick up "mm: fix

2024-07-06T18:44:41+00:00

crashes from deferred split racing folio migration", needed by "mm:
migrate: split folio_migrate_mapping()".

mm/readahead: limit page cache size in page_cache_ra_order()

2024-07-04T05:40:37+00:00

In page_cache_ra_order(), the maximal order of the page cache to be
allocated shouldn't be larger than MAX_PAGECACHE_ORDER.  Otherwise, it's
possible the large page cache can't be supported by xarray when the
corresponding xarray entry is split.

For example, HPAGE_PMD_ORDER is 13 on ARM64 when the base page size is
64KB.  The PMD-sized page cache can't be supported by xarray.

Link: https://lkml.kernel.org/r/20240627003953.1262512-3-gshan@redhat.com
Fixes: 793917d997df ("mm/readahead: Add large folio readahead")
Signed-off-by: Gavin Shan 
Acked-by: David Hildenbrand 
Cc: Darrick J. Wong 
Cc: Don Dutile 
Cc: Hugh Dickins 
Cc: Linus Torvalds 
Cc: Matthew Wilcox (Oracle) 
Cc: Ryan Roberts 
Cc: William Kucharski 
Cc: Zhenyu Zhang 
Cc: 	[5.18+]
Signed-off-by: Andrew Morton

readahead: simplify gotos in page_cache_sync_ra()

2024-07-04T02:30:28+00:00

Unify all conditions for initial readahead to simplify goto logic in
page_cache_sync_ra().  No functional changes.

Link: https://lkml.kernel.org/r/20240625101909.12234-10-jack@suse.cz
Signed-off-by: Jan Kara 
Reviewed-by: Josef Bacik 
Tested-by: Zhang Peng 
Cc: Matthew Wilcox (Oracle) 
Signed-off-by: Andrew Morton

readahead: fold try_context_readahead() into its single caller

2024-07-04T02:30:28+00:00

try_context_readahead() has a single caller page_cache_sync_ra().  Fold
the function there to make ra state modifications more obvious.  No
functional changes.

Link: https://lkml.kernel.org/r/20240625101909.12234-9-jack@suse.cz
Signed-off-by: Jan Kara 
Reviewed-by: Josef Bacik 
Tested-by: Zhang Peng 
Cc: Matthew Wilcox (Oracle) 
Signed-off-by: Andrew Morton

readahead: disentangle async and sync readahead

2024-07-04T02:30:27+00:00

Both async and sync readahead are handled by ondemand_readahead()
function.  However there isn't actually much in common.  Just move async
related parts into page_cache_ra_async() and sync related parts to
page_cache_ra_sync().  No functional changes.

Link: https://lkml.kernel.org/r/20240625101909.12234-8-jack@suse.cz
Signed-off-by: Jan Kara 
Reviewed-by: Josef Bacik 
Tested-by: Zhang Peng 
Cc: Matthew Wilcox (Oracle) 
Signed-off-by: Andrew Morton

readahead: drop dead code in ondemand_readahead()

2024-07-04T02:30:27+00:00

ondemand_readahead() scales up the readahead window if the current read
would hit the readahead mark placed by itself.  However the condition is
mostly dead code because:

a) In case of async readahead we always increase ra->start so ra->start
   == index is never true.

b) In case of sync readahead we either go through
   try_context_readahead() in which case ra->async_size == 1 < ra->size or
   we go through initial_readahead where ra->async_size == ra->size iff
   ra->size == max_pages.

So the only practical effect is reducing async_size for large initial
reads.  Make the code more obvious.

Link: https://lkml.kernel.org/r/20240625101909.12234-7-jack@suse.cz
Signed-off-by: Jan Kara 
Reviewed-by: Josef Bacik 
Tested-by: Zhang Peng 
Cc: Matthew Wilcox (Oracle) 
Signed-off-by: Andrew Morton