linux-toradex.git/fs/nfs/fscache.c, branch v3.7.2

NFS: Don't pass mount data to nfs_fscache_get_super_cookie()

2012-05-15T00:30:26+00:00

I intend on creating a single nfs_fs_mount() function used by all our
mount paths.  To avoid checking between new mounts and clone mounts, I
instead pass both structures to a new function in super.c that finds the
cache key and then looks up the super cookie.

Signed-off-by: Bryan Schumaker 
Signed-off-by: Trond Myklebust

NFS: Fix more NFS debug related build warnings

2012-03-21T13:31:44+00:00

Signed-off-by: Trond Myklebust

FS-Cache: Add a helper to bulk uncache pages on an inode

2011-07-07T20:21:56+00:00

Add an FS-Cache helper to bulk uncache pages on an inode.  This will
only work for the circumstance where the pages in the cache correspond
1:1 with the pages attached to an inode's page cache.

This is required for CIFS and NFS: When disabling inode cookie, we were
returning the cookie and setting cifsi->fscache to NULL but failed to
invalidate any previously mapped pages.  This resulted in "Bad page
state" errors and manifested in other kind of errors when running
fsstress.  Fix it by uncaching mapped pages when we disable the inode
cookie.

This patch should fix the following oops and "Bad page state" errors
seen during fsstress testing.

  ------------[ cut here ]------------
  kernel BUG at fs/cachefiles/namei.c:201!
  invalid opcode: 0000 [#1] SMP
  Pid: 5, comm: kworker/u:0 Not tainted 2.6.38.7-30.fc15.x86_64 #1 Bochs Bochs
  RIP: 0010: cachefiles_walk_to_object+0x436/0x745 [cachefiles]
  RSP: 0018:ffff88002ce6dd00  EFLAGS: 00010282
  RAX: ffff88002ef165f0 RBX: ffff88001811f500 RCX: 0000000000000000
  RDX: 0000000000000000 RSI: 0000000000000100 RDI: 0000000000000282
  RBP: ffff88002ce6dda0 R08: 0000000000000100 R09: ffffffff81b3a300
  R10: 0000ffff00066c0a R11: 0000000000000003 R12: ffff88002ae54840
  R13: ffff88002ae54840 R14: ffff880029c29c00 R15: ffff88001811f4b0
  FS:  00007f394dd32720(0000) GS:ffff88002ef00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
  CR2: 00007fffcb62ddf8 CR3: 000000001825f000 CR4: 00000000000006e0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
  Process kworker/u:0 (pid: 5, threadinfo ffff88002ce6c000, task ffff88002ce55cc0)
  Stack:
   0000000000000246 ffff88002ce55cc0 ffff88002ce6dd58 ffff88001815dc00
   ffff8800185246c0 ffff88001811f618 ffff880029c29d18 ffff88001811f380
   ffff88002ce6dd50 ffffffff814757e4 ffff88002ce6dda0 ffffffff8106ac56
  Call Trace:
   cachefiles_lookup_object+0x78/0xd4 [cachefiles]
   fscache_lookup_object+0x131/0x16d [fscache]
   fscache_object_work_func+0x1bc/0x669 [fscache]
   process_one_work+0x186/0x298
   worker_thread+0xda/0x15d
   kthread+0x84/0x8c
   kernel_thread_helper+0x4/0x10
  RIP  cachefiles_walk_to_object+0x436/0x745 [cachefiles]
  ---[ end trace 1d481c9af1804caa ]---

I tested the uncaching by the following means:

 (1) Create a big file on my NFS server (104857600 bytes).

 (2) Read the file into the cache with md5sum on the NFS client.  Look in
     /proc/fs/fscache/stats:

	Pages  : mrk=25601 unc=0

 (3) Open the file for read/write ("bash 5<>/warthog/bigfile").  Look in proc
     again:

	Pages  : mrk=25601 unc=25601

Reported-by: Jeff Layton 
Signed-off-by: David Howells 
Reviewed-and-Tested-by: Suresh Jayaraman 
cc: stable@kernel.org
Signed-off-by: Linus Torvalds

NFS: Squelch compiler warning

2010-05-14T19:09:31+00:00

Seen with -Wextra:

/home/cel/linux/fs/nfs/fscache.c: In function ‘__nfs_readpages_from_fscache’:
/home/cel/linux/fs/nfs/fscache.c:479: warning: comparison between signed and unsigned integer expressions

The comparison implicitly converts "int" to "unsigned", making it
safe.  But there's no need for the implicit type conversions here, and
the dfprintk() already uses a "%u" formatter for "npages."  Better to
reduce confusion.

Signed-off-by: Chuck Lever 
Signed-off-by: Trond Myklebust

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

2010-03-30T13:02:32+00:00

percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.

Signed-off-by: Tejun Heo 
Guess-its-ok-by: Christoph Lameter 
Cc: Ingo Molnar 
Cc: Lee Schermerhorn

NFS: Fix a bug in nfs_fscache_release_page()

2010-02-09T19:29:10+00:00

Not having an fscache cookie is perfectly valid if the user didn't mount
with the fscache option.

This patch fixes http://bugzilla.kernel.org/show_bug.cgi?id=15234

Signed-off-by: Trond Myklebust 
Acked-by: David Howells 
Cc: stable@kernel.org

FS-Cache: Handle pages pending storage that get evicted under OOM conditions

2009-11-19T18:11:35+00:00

Handle netfs pages that the vmscan algorithm wants to evict from the pagecache
under OOM conditions, but that are waiting for write to the cache.  Under these
conditions, vmscan calls the releasepage() function of the netfs, asking if a
page can be discarded.

The problem is typified by the following trace of a stuck process:

	kslowd005     D 0000000000000000     0  4253      2 0x00000080
	 ffff88001b14f370 0000000000000046 ffff880020d0d000 0000000000000007
	 0000000000000006 0000000000000001 ffff88001b14ffd8 ffff880020d0d2a8
	 000000000000ddf0 00000000000118c0 00000000000118c0 ffff880020d0d2a8
	Call Trace:
	 [] __fscache_wait_on_page_write+0x8b/0xa7 [fscache]
	 [] ? autoremove_wake_function+0x0/0x34
	 [] ? __fscache_check_page_write+0x63/0x70 [fscache]
	 [] nfs_fscache_release_page+0x4e/0xc4 [nfs]
	 [] nfs_release_page+0x3c/0x41 [nfs]
	 [] try_to_release_page+0x32/0x3b
	 [] shrink_page_list+0x316/0x4ac
	 [] shrink_inactive_list+0x392/0x67c
	 [] ? __mutex_unlock_slowpath+0x100/0x10b
	 [] ? trace_hardirqs_on_caller+0x10c/0x130
	 [] ? mutex_unlock+0x9/0xb
	 [] shrink_list+0x8d/0x8f
	 [] shrink_zone+0x278/0x33c
	 [] ? ktime_get_ts+0xad/0xba
	 [] try_to_free_pages+0x22e/0x392
	 [] ? isolate_pages_global+0x0/0x212
	 [] __alloc_pages_nodemask+0x3dc/0x5cf
	 [] grab_cache_page_write_begin+0x65/0xaa
	 [] ext3_write_begin+0x78/0x1eb
	 [] generic_file_buffered_write+0x109/0x28c
	 [] ? current_fs_time+0x22/0x29
	 [] __generic_file_aio_write+0x350/0x385
	 [] ? generic_file_aio_write+0x4a/0xae
	 [] generic_file_aio_write+0x60/0xae
	 [] do_sync_write+0xe3/0x120
	 [] ? autoremove_wake_function+0x0/0x34
	 [] ? __dentry_open+0x1a5/0x2b8
	 [] ? dentry_open+0x82/0x89
	 [] cachefiles_write_page+0x298/0x335 [cachefiles]
	 [] fscache_write_op+0x178/0x2c2 [fscache]
	 [] fscache_op_execute+0x7a/0xd1 [fscache]
	 [] slow_work_execute+0x18f/0x2d1
	 [] slow_work_thread+0x1c5/0x308
	 [] ? autoremove_wake_function+0x0/0x34
	 [] ? slow_work_thread+0x0/0x308
	 [] kthread+0x7a/0x82
	 [] child_rip+0xa/0x20
	 [] ? restore_args+0x0/0x30
	 [] ? tg_shares_up+0x171/0x227
	 [] ? kthread+0x0/0x82
	 [] ? child_rip+0x0/0x20

In the above backtrace, the following is happening:

 (1) A page storage operation is being executed by a slow-work thread
     (fscache_write_op()).

 (2) FS-Cache farms the operation out to the cache to perform
     (cachefiles_write_page()).

 (3) CacheFiles is then calling Ext3 to perform the actual write, using Ext3's
     standard write (do_sync_write()) under KERNEL_DS directly from the netfs
     page.

 (4) However, for Ext3 to perform the write, it must allocate some memory, in
     particular, it must allocate at least one page cache page into which it
     can copy the data from the netfs page.

 (5) Under OOM conditions, the memory allocator can't immediately come up with
     a page, so it uses vmscan to find something to discard
     (try_to_free_pages()).

 (6) vmscan finds a clean netfs page it might be able to discard (possibly the
     one it's trying to write out).

 (7) The netfs is called to throw the page away (nfs_release_page()) - but it's
     called with __GFP_WAIT, so the netfs decides to wait for the store to
     complete (__fscache_wait_on_page_write()).

 (8) This blocks a slow-work processing thread - possibly against itself.

The system ends up stuck because it can't write out any netfs pages to the
cache without allocating more memory.

To avoid this, we make FS-Cache cancel some writes that aren't in the middle of
actually being performed.  This means that some data won't make it into the
cache this time.  To support this, a new FS-Cache function is added
fscache_maybe_release_page() that replaces what the netfs releasepage()
functions used to do with respect to the cache.

The decisions fscache_maybe_release_page() makes are counted and displayed
through /proc/fs/fscache/stats on a line labelled "VmScan".  There are four
counters provided: "nos=N" - pages that weren't pending storage; "gon=N" -
pages that were pending storage when we first looked, but weren't by the time
we got the object lock; "bsy=N" - pages that we ignored as they were actively
being written when we looked; and "can=N" - pages that we cancelled the storage
of.

What I'd really like to do is alter the behaviour of the cancellation
heuristics, depending on how necessary it is to expel pages.  If there are
plenty of other pages that aren't waiting to be written to the cache that
could be ejected first, then it would be nice to hold up on immediate
cancellation of cache writes - but I don't see a way of doing that.

Signed-off-by: David Howells

NFS: Propagate 'fsc' mount option through automounts

2009-09-23T18:36:39+00:00

Propagate the NFS 'fsc' mount option through NFS automounts of various types.

This is now required as commit:

	commit c02d7adf8c5429727a98bad1d039bccad4c61c50
	Author: Trond Myklebust 
	Date:   Mon Jun 22 15:09:14 2009 -0400

	NFSv4: Replace nfs4_path_walk() with VFS path lookup in a private namespace

uses VFS-driven automounting to reach all submounts barring the root, thus
preventing fscaching from being enabled on any submount other than the root.

This patch gets around that by propagating the NFS_OPTION_FSCACHE flag across
automounts.  If a uniquifier is supplied to a mount then this is propagated to
all automounts of that mount too.

Signed-off-by: David Howells 
[Trond: Fixed up the definition of nfs_fscache_get_super_cookie for the
        case of #undef CONFIG_NFS_FSCACHE]
Signed-off-by: Trond Myklebust

NFS: Store pages from an NFS inode into a local cache

2009-04-03T15:42:45+00:00

Store pages from an NFS inode into the cache data storage object associated
with that inode.

Signed-off-by: David Howells 
Acked-by: Steve Dickson 
Acked-by: Trond Myklebust 
Acked-by: Al Viro 
Tested-by: Daire Byrne

NFS: Read pages from FS-Cache into an NFS inode

2009-04-03T15:42:44+00:00

Read pages from an FS-Cache data storage object representing an inode into an
NFS inode.

Signed-off-by: David Howells 
Acked-by: Steve Dickson 
Acked-by: Trond Myklebust 
Acked-by: Al Viro 
Tested-by: Daire Byrne