1. 30 Nov, 2009 8 commits
  2. 23 Nov, 2009 3 commits
  3. 20 Nov, 2009 9 commits
  4. 19 Nov, 2009 20 commits
    • Jiang Yutang's avatar
      sata_fsl: Split hard and soft reset · a0a74d1e
      Jiang Yutang authored
      
      
      Split sata_fsl_softreset() into hard and soft resets to make
      error-handling more efficient & device and PMP detection more
      reliable.
      
      Also includes fix for PMP support, driver tested with Sil3726,
      Sil4726 & Exar PMP controllers.
      
      [AV: Also fixes resuming from deep sleep on MPC8315 CPUs]
      Signed-off-by: default avatarJiang Yutang <b14898@freescale.com>
      Signed-off-by: default avatarAnton Vorontsov <avorontsov@ru.mvista.com>
      Signed-off-by: default avatarJeff Garzik <jgarzik@redhat.com>
      a0a74d1e
    • Linus Torvalds's avatar
      Linux 2.6.32-rc8 · 648f4e3e
      Linus Torvalds authored
      648f4e3e
    • Linus Torvalds's avatar
      Merge branch 'bugfixes' of git://git.linux-nfs.org/projects/trondmy/nfs-2.6 · e6236f78
      Linus Torvalds authored
      * 'bugfixes' of git://git.linux-nfs.org/projects/trondmy/nfs-2.6:
        SUNRPC: Address buffer overrun in rpc_uaddr2sockaddr()
        NFSv4: Fix a cache validation bug which causes getcwd() to return ENOENT
      e6236f78
    • Alan Cox's avatar
      vt: Fix use of "new" in a struct field · 308efab5
      Alan Cox authored
      
      
      As this struct is exposed to user space and the API was added for this
      release it's a bit of a pain for the C++ world and we still have time to
      fix it. Rename the fields before we end up with that pain in an actual
      release.
      Signed-off-by: default avatarAlan Cox <alan@linux.intel.com>
      Reported-by: Olivier Goffart
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      308efab5
    • David Woodhouse's avatar
      Fix handling of the HP/Acer 'DMAR at zero' BIOS error for machines with <4GiB RAM. · 5854d9c8
      David Woodhouse authored
      Commit 86cf898e
      
       ("intel-iommu: Check for
      'DMAR at zero' BIOS error earlier.") was supposed to work by pretending
      not to detect an IOMMU if it was actually being reported by the BIOS at
      physical address zero.
      
      However, the intel_iommu_init() function is called unconditionally, as
      are the corresponding functions for other IOMMU hardware.
      
      So the patch only worked if you have RAM above the 4GiB boundary. It
      caused swiotlb to be initialised when no IOMMU was detected during early
      boot, and thus the later IOMMU init would refuse to run.
      
      But if you have less RAM than that, swiotlb wouldn't get set up and the
      IOMMU _would_ still end up being initialised, even though we never
      claimed to detect it.
      
      This patch also sets the dmar_disabled flag when the error is detected
      during the initial detection phase -- so that the later call to
      intel_iommu_init() will return without doing anything, regardless of
      whether swiotlb is used or not.
      Signed-off-by: default avatarDavid Woodhouse <David.Woodhouse@intel.com>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      5854d9c8
    • David Howells's avatar
      CacheFiles: Don't log lookup/create failing with ENOBUFS · 14e69647
      David Howells authored
      
      
      Don't log the CacheFiles lookup/create object routined failing with ENOBUFS as
      under high memory load or high cache load they can do this quite a lot.  This
      error simply means that the requested object cannot be created on disk due to
      lack of space, or due to failure of the backing filesystem to find sufficient
      resources.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      14e69647
    • David Howells's avatar
      CacheFiles: Catch an overly long wait for an old active object · fee096de
      David Howells authored
      
      
      Catch an overly long wait for an old, dying active object when we want to
      replace it with a new one.  The probability is that all the slow-work threads
      are hogged, and the delete can't get a look in.
      
      What we do instead is:
      
       (1) if there's nothing in the slow work queue, we sleep until either the dying
           object has finished dying or there is something in the slow work queue
           behind which we can queue our object.
      
       (2) if there is something in the slow work queue, we return ETIMEDOUT to
           fscache_lookup_object(), which then puts us back on the slow work queue,
           presumably behind the deletion that we're blocked by.  We are then
           deferred for a while until we work our way back through the queue -
           without blocking a slow-work thread unnecessarily.
      
      A backtrace similar to the following may appear in the log without this patch:
      
      	INFO: task kslowd004:5711 blocked for more than 120 seconds.
      	"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
      	kslowd004     D 0000000000000000     0  5711      2 0x00000080
      	 ffff88000340bb80 0000000000000046 ffff88002550d000 0000000000000000
      	 ffff88002550d000 0000000000000007 ffff88000340bfd8 ffff88002550d2a8
      	 000000000000ddf0 00000000000118c0 00000000000118c0 ffff88002550d2a8
      	Call Trace:
      	 [<ffffffff81058e21>] ? trace_hardirqs_on+0xd/0xf
      	 [<ffffffffa011c4d8>] ? cachefiles_wait_bit+0x0/0xd [cachefiles]
      	 [<ffffffffa011c4e1>] cachefiles_wait_bit+0x9/0xd [cachefiles]
      	 [<ffffffff81353153>] __wait_on_bit+0x43/0x76
      	 [<ffffffff8111ae39>] ? ext3_xattr_get+0x1ec/0x270
      	 [<ffffffff813531ef>] out_of_line_wait_on_bit+0x69/0x74
      	 [<ffffffffa011c4d8>] ? cachefiles_wait_bit+0x0/0xd [cachefiles]
      	 [<ffffffff8104c125>] ? wake_bit_function+0x0/0x2e
      	 [<ffffffffa011bc79>] cachefiles_mark_object_active+0x203/0x23b [cachefiles]
      	 [<ffffffffa011c209>] cachefiles_walk_to_object+0x558/0x827 [cachefiles]
      	 [<ffffffffa011a429>] cachefiles_lookup_object+0xac/0x12a [cachefiles]
      	 [<ffffffffa00aa1e9>] fscache_lookup_object+0x1c7/0x214 [fscache]
      	 [<ffffffffa00aafc5>] fscache_object_state_machine+0xa5/0x52d [fscache]
      	 [<ffffffffa00ab4ac>] fscache_object_slow_work_execute+0x5f/0xa0 [fscache]
      	 [<ffffffff81082093>] slow_work_execute+0x18f/0x2d1
      	 [<ffffffff8108239a>] slow_work_thread+0x1c5/0x308
      	 [<ffffffff8104c0f1>] ? autoremove_wake_function+0x0/0x34
      	 [<ffffffff810821d5>] ? slow_work_thread+0x0/0x308
      	 [<ffffffff8104be91>] kthread+0x7a/0x82
      	 [<ffffffff8100beda>] child_rip+0xa/0x20
      	 [<ffffffff8100b87c>] ? restore_args+0x0/0x30
      	 [<ffffffff8104be17>] ? kthread+0x0/0x82
      	 [<ffffffff8100bed0>] ? child_rip+0x0/0x20
      	1 lock held by kslowd004/5711:
      	 #0:  (&sb->s_type->i_mutex_key#7/1){+.+.+.}, at: [<ffffffffa011be64>] cachefiles_walk_to_object+0x1b3/0x827 [cachefiles]
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      fee096de
    • David Howells's avatar
      CacheFiles: Better showing of debugging information in active object problems · d0e27b78
      David Howells authored
      
      
      Show more debugging information if cachefiles_mark_object_active() is asked to
      activate an active object.
      
      This may happen, for instance, if the netfs tries to register an object with
      the same key multiple times.
      
      The code is changed to (a) get the appropriate object lock to protect the
      cookie pointer whilst we dereference it, and (b) get and display the cookie key
      if available.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      d0e27b78
    • David Howells's avatar
      CacheFiles: Mark parent directory locks as I_MUTEX_PARENT to keep lockdep happy · 6511de33
      David Howells authored
      
      
      Mark parent directory locks as I_MUTEX_PARENT in the callers of
      cachefiles_bury_object() so that lockdep doesn't complain when that invokes
      vfs_unlink():
      
      =============================================
      [ INFO: possible recursive locking detected ]
      2.6.32-rc6-cachefs #47
      ---------------------------------------------
      kslowd002/3089 is trying to acquire lock:
       (&sb->s_type->i_mutex_key#7){+.+.+.}, at: [<ffffffff810bbf72>] vfs_unlink+0x8b/0x128
      
      but task is already holding lock:
       (&sb->s_type->i_mutex_key#7){+.+.+.}, at: [<ffffffffa00e4e61>] cachefiles_walk_to_object+0x1b0/0x831 [cachefiles]
      
      other info that might help us debug this:
      1 lock held by kslowd002/3089:
       #0:  (&sb->s_type->i_mutex_key#7){+.+.+.}, at: [<ffffffffa00e4e61>] cachefiles_walk_to_object+0x1b0/0x831 [cachefiles]
      
      stack backtrace:
      Pid: 3089, comm: kslowd002 Not tainted 2.6.32-rc6-cachefs #47
      Call Trace:
       [<ffffffff8105ad7b>] __lock_acquire+0x1649/0x16e3
       [<ffffffff8118170e>] ? inode_has_perm+0x5f/0x61
       [<ffffffff8105ae6c>] lock_acquire+0x57/0x6d
       [<ffffffff810bbf72>] ? vfs_unlink+0x8b/0x128
       [<ffffffff81353ac3>] mutex_lock_nested+0x54/0x292
       [<ffffffff810bbf72>] ? vfs_unlink+0x8b/0x128
       [<ffffffff8118179e>] ? selinux_inode_permission+0x8e/0x90
       [<ffffffff8117e271>] ? security_inode_permission+0x1c/0x1e
       [<ffffffff810bb4fb>] ? inode_permission+0x99/0xa5
       [<ffffffff810bbf72>] vfs_unlink+0x8b/0x128
       [<ffffffff810adb19>] ? kfree+0xed/0xf9
       [<ffffffffa00e3f00>] cachefiles_bury_object+0xb6/0x420 [cachefiles]
       [<ffffffff81058e21>] ? trace_hardirqs_on+0xd/0xf
       [<ffffffffa00e7e24>] ? cachefiles_check_object_xattr+0x233/0x293 [cachefiles]
       [<ffffffffa00e51b0>] cachefiles_walk_to_object+0x4ff/0x831 [cachefiles]
       [<ffffffff81032238>] ? finish_task_switch+0x0/0xb2
       [<ffffffffa00e3429>] cachefiles_lookup_object+0xac/0x12a [cachefiles]
       [<ffffffffa00741e9>] fscache_lookup_object+0x1c7/0x214 [fscache]
       [<ffffffffa0074fc5>] fscache_object_state_machine+0xa5/0x52d [fscache]
       [<ffffffffa00754ac>] fscache_object_slow_work_execute+0x5f/0xa0 [fscache]
       [<ffffffff81082093>] slow_work_execute+0x18f/0x2d1
       [<ffffffff8108239a>] slow_work_thread+0x1c5/0x308
       [<ffffffff8104c0f1>] ? autoremove_wake_function+0x0/0x34
       [<ffffffff810821d5>] ? slow_work_thread+0x0/0x308
       [<ffffffff8104be91>] kthread+0x7a/0x82
       [<ffffffff8100beda>] child_rip+0xa/0x20
       [<ffffffff8100b87c>] ? restore_args+0x0/0x30
       [<ffffffff8104be17>] ? kthread+0x0/0x82
       [<ffffffff8100bed0>] ? child_rip+0x0/0x20
      Signed-off-by: default avatarDaivd Howells <dhowells@redhat.com>
      6511de33
    • David Howells's avatar
      CacheFiles: Handle truncate unlocking the page we're reading · 5e929b33
      David Howells authored
      Handle truncate unlocking the page we're attempting to read from the backing
      device before the read has completed.
      
      This was causing reports like the following to occur:
      
      	Pid: 4765, comm: kslowd Not tainted 2.6.30.1 #1
      
      
      	Call Trace:
      	 [<ffffffffa0331d7a>] ? cachefiles_read_waiter+0xd9/0x147 [cachefiles]
      	 [<ffffffff804b74bd>] ? __wait_on_bit+0x60/0x6f
      	 [<ffffffff8022bbbb>] ? __wake_up_common+0x3f/0x71
      	 [<ffffffff8022cc32>] ? __wake_up+0x30/0x44
      	 [<ffffffff8024a41f>] ? __wake_up_bit+0x28/0x2d
      	 [<ffffffffa003a793>] ? ext3_truncate+0x4d7/0x8ed [ext3]
      	 [<ffffffff80281f90>] ? pagevec_lookup+0x17/0x1f
      	 [<ffffffff8028c2ff>] ? unmap_mapping_range+0x59/0x1ff
      	 [<ffffffff8022cc32>] ? __wake_up+0x30/0x44
      	 [<ffffffff8028e286>] ? vmtruncate+0xc2/0xe2
      	 [<ffffffff802b82cf>] ? inode_setattr+0x22/0x10a
      	 [<ffffffffa003baa5>] ? ext3_setattr+0x17b/0x1e6 [ext3]
      	 [<ffffffff802b853d>] ? notify_change+0x186/0x2c9
      	 [<ffffffffa032d9de>] ? cachefiles_attr_changed+0x133/0x1cd [cachefiles]
      	 [<ffffffffa032df7f>] ? cachefiles_lookup_object+0xcf/0x12a [cachefiles]
      	 [<ffffffffa0318165>] ? fscache_lookup_object+0x110/0x122 [fscache]
      	 [<ffffffffa03188c3>] ? fscache_object_slow_work_execute+0x590/0x6bc
      	[fscache]
      	 [<ffffffff80278f82>] ? slow_work_thread+0x285/0x43a
      	 [<ffffffff8024a446>] ? autoremove_wake_function+0x0/0x2e
      	 [<ffffffff80278cfd>] ? slow_work_thread+0x0/0x43a
      	 [<ffffffff8024a317>] ? kthread+0x54/0x81
      	 [<ffffffff8020c93a>] ? child_rip+0xa/0x20
      	 [<ffffffff8024a2c3>] ? kthread+0x0/0x81
      	 [<ffffffff8020c930>] ? child_rip+0x0/0x20
      	CacheFiles: I/O Error: Readpage failed on backing file 200000000000810
      	FS-Cache: Cache cachefiles stopped due to I/O error
      Reported-by: default avatarChristian Kujau <lists@nerdbynature.de>
      Reported-by: Takashi Iwai's avatarTakashi Iwai <tiwai@suse.de>
      Reported-by: default avatarDuc Le Minh <duclm.vn@gmail.com>
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      5e929b33
    • David Howells's avatar
      CacheFiles: Don't write a full page if there's only a partial page to cache · a17754fb
      David Howells authored
      
      
      cachefiles_write_page() writes a full page to the backing file for the last
      page of the netfs file, even if the netfs file's last page is only a partial
      page.
      
      This causes the EOF on the backing file to be extended beyond the EOF of the
      netfs, and thus the backing file will be truncated by cachefiles_attr_changed()
      called from cachefiles_lookup_object().
      
      So we need to limit the write we make to the backing file on that last page
      such that it doesn't push the EOF too far.
      
      Also, if a backing file that has a partial page at the end is expanded, we
      discard the partial page and refetch it on the basis that we then have a hole
      in the file with invalid data, and should the power go out...  A better way to
      deal with this could be to record a note that the partial page contains invalid
      data until the correct data is written into it.
      
      This isn't a problem for netfs's that discard the whole backing file if the
      file size changes (such as NFS).
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      a17754fb
    • David Howells's avatar
      FS-Cache: Actually requeue an object when requested · 868411be
      David Howells authored
      
      
      FS-Cache objects have an FSCACHE_OBJECT_EV_REQUEUE event that can theoretically
      be raised to ask the state machine to requeue the object for further processing
      before the work function returns to the slow-work facility.
      
      However, fscache_object_work_execute() was clearing that bit before checking
      the event mask to see whether the object has any pending events that require it
      to be requeued immediately.
      
      Instead, the bit should be cleared after the check and enqueue.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      868411be
    • David Howells's avatar
      FS-Cache: Start processing an object's operations on that object's death · 60d543ca
      David Howells authored
      
      
      Start processing an object's operations when that object moves into the DYING
      state as the object cannot be destroyed until all its outstanding operations
      have completed.
      
      Furthermore, make sure that read and allocation operations handle being woken
      up on a dead object.  Such events are recorded in the Allocs.abt and
      Retrvls.abt statistics as viewable through /proc/fs/fscache/stats.
      
      The code for waiting for object activation for the read and allocation
      operations is also extracted into its own function as it is much the same in
      all cases, differing only in the stats incremented.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      60d543ca
    • David Howells's avatar
      FS-Cache: Make sure FSCACHE_COOKIE_LOOKING_UP cleared on lookup failure · d461d26d
      David Howells authored
      
      
      We must make sure that FSCACHE_COOKIE_LOOKING_UP is cleared on lookup failure
      (if an object reaches the LC_DYING state), and we should clear it before
      clearing FSCACHE_COOKIE_CREATING.
      
      If this doesn't happen then fscache_wait_for_deferred_lookup() may hold
      allocation and retrieval operations indefinitely until they're interrupted by
      signals - which in turn pins the dying object until they go away.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      d461d26d
    • David Howells's avatar
      FS-Cache: Add a retirement stat counter · 2175bb06
      David Howells authored
      
      
      Add a stat counter to count retirement events rather than ordinary release
      events (the retire argument to fscache_relinquish_cookie()).
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      2175bb06
    • David Howells's avatar
      FS-Cache: Handle pages pending storage that get evicted under OOM conditions · 201a1542
      David Howells authored
      
      
      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:
      	 [<ffffffffa00782d8>] __fscache_wait_on_page_write+0x8b/0xa7 [fscache]
      	 [<ffffffff8104c0f1>] ? autoremove_wake_function+0x0/0x34
      	 [<ffffffffa0078240>] ? __fscache_check_page_write+0x63/0x70 [fscache]
      	 [<ffffffffa00b671d>] nfs_fscache_release_page+0x4e/0xc4 [nfs]
      	 [<ffffffffa00927f0>] nfs_release_page+0x3c/0x41 [nfs]
      	 [<ffffffff810885d3>] try_to_release_page+0x32/0x3b
      	 [<ffffffff81093203>] shrink_page_list+0x316/0x4ac
      	 [<ffffffff8109372b>] shrink_inactive_list+0x392/0x67c
      	 [<ffffffff813532fa>] ? __mutex_unlock_slowpath+0x100/0x10b
      	 [<ffffffff81058df0>] ? trace_hardirqs_on_caller+0x10c/0x130
      	 [<ffffffff8135330e>] ? mutex_unlock+0x9/0xb
      	 [<ffffffff81093aa2>] shrink_list+0x8d/0x8f
      	 [<ffffffff81093d1c>] shrink_zone+0x278/0x33c
      	 [<ffffffff81052d6c>] ? ktime_get_ts+0xad/0xba
      	 [<ffffffff81094b13>] try_to_free_pages+0x22e/0x392
      	 [<ffffffff81091e24>] ? isolate_pages_global+0x0/0x212
      	 [<ffffffff8108e743>] __alloc_pages_nodemask+0x3dc/0x5cf
      	 [<ffffffff81089529>] grab_cache_page_write_begin+0x65/0xaa
      	 [<ffffffff8110f8c0>] ext3_write_begin+0x78/0x1eb
      	 [<ffffffff81089ec5>] generic_file_buffered_write+0x109/0x28c
      	 [<ffffffff8103cb69>] ? current_fs_time+0x22/0x29
      	 [<ffffffff8108a509>] __generic_file_aio_write+0x350/0x385
      	 [<ffffffff8108a588>] ? generic_file_aio_write+0x4a/0xae
      	 [<ffffffff8108a59e>] generic_file_aio_write+0x60/0xae
      	 [<ffffffff810b2e82>] do_sync_write+0xe3/0x120
      	 [<ffffffff8104c0f1>] ? autoremove_wake_function+0x0/0x34
      	 [<ffffffff810b18e1>] ? __dentry_open+0x1a5/0x2b8
      	 [<ffffffff810b1a76>] ? dentry_open+0x82/0x89
      	 [<ffffffffa00e693c>] cachefiles_write_page+0x298/0x335 [cachefiles]
      	 [<ffffffffa0077147>] fscache_write_op+0x178/0x2c2 [fscache]
      	 [<ffffffffa0075656>] fscache_op_execute+0x7a/0xd1 [fscache]
      	 [<ffffffff81082093>] slow_work_execute+0x18f/0x2d1
      	 [<ffffffff8108239a>] slow_work_thread+0x1c5/0x308
      	 [<ffffffff8104c0f1>] ? autoremove_wake_function+0x0/0x34
      	 [<ffffffff810821d5>] ? slow_work_thread+0x0/0x308
      	 [<ffffffff8104be91>] kthread+0x7a/0x82
      	 [<ffffffff8100beda>] child_rip+0xa/0x20
      	 [<ffffffff8100b87c>] ? restore_args+0x0/0x30
      	 [<ffffffff8102ef83>] ? tg_shares_up+0x171/0x227
      	 [<ffffffff8104be17>] ? kthread+0x0/0x82
      	 [<ffffffff8100bed0>] ? 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: default avatarDavid Howells <dhowells@redhat.com>
      201a1542
    • David Howells's avatar
      FS-Cache: Handle read request vs lookup, creation or other cache failure · e3d4d28b
      David Howells authored
      
      
      FS-Cache doesn't correctly handle the netfs requesting a read from the cache
      on an object that failed or was withdrawn by the cache.  A trace similar to
      the following might be seen:
      
      	CacheFiles: Lookup failed error -105
      	[exe   ] unexpected submission OP165afe [OBJ6cac OBJECT_LC_DYING]
      	[exe   ] objstate=OBJECT_LC_DYING [OBJECT_LC_DYING]
      	[exe   ] objflags=0
      	[exe   ] objevent=9 [fffffffffffffffb]
      	[exe   ] ops=0 inp=0 exc=0
      	Pid: 6970, comm: exe Not tainted 2.6.32-rc6-cachefs #50
      	Call Trace:
      	 [<ffffffffa0076477>] fscache_submit_op+0x3ff/0x45a [fscache]
      	 [<ffffffffa0077997>] __fscache_read_or_alloc_pages+0x187/0x3c4 [fscache]
      	 [<ffffffffa00b6480>] ? nfs_readpage_from_fscache_complete+0x0/0x66 [nfs]
      	 [<ffffffffa00b6388>] __nfs_readpages_from_fscache+0x7e/0x176 [nfs]
      	 [<ffffffff8108e483>] ? __alloc_pages_nodemask+0x11c/0x5cf
      	 [<ffffffffa009d796>] nfs_readpages+0x114/0x1d7 [nfs]
      	 [<ffffffff81090314>] __do_page_cache_readahead+0x15f/0x1ec
      	 [<ffffffff81090228>] ? __do_page_cache_readahead+0x73/0x1ec
      	 [<ffffffff810903bd>] ra_submit+0x1c/0x20
      	 [<ffffffff810906bb>] ondemand_readahead+0x227/0x23a
      	 [<ffffffff81090762>] page_cache_sync_readahead+0x17/0x19
      	 [<ffffffff8108a99e>] generic_file_aio_read+0x236/0x5a0
      	 [<ffffffffa00937bd>] nfs_file_read+0xe4/0xf3 [nfs]
      	 [<ffffffff810b2fa2>] do_sync_read+0xe3/0x120
      	 [<ffffffff81354cc3>] ? _spin_unlock_irq+0x2b/0x31
      	 [<ffffffff8104c0f1>] ? autoremove_wake_function+0x0/0x34
      	 [<ffffffff811848e5>] ? selinux_file_permission+0x5d/0x10f
      	 [<ffffffff81352bdb>] ? thread_return+0x3e/0x101
      	 [<ffffffff8117d7b0>] ? security_file_permission+0x11/0x13
      	 [<ffffffff810b3b06>] vfs_read+0xaa/0x16f
      	 [<ffffffff81058df0>] ? trace_hardirqs_on_caller+0x10c/0x130
      	 [<ffffffff810b3c84>] sys_read+0x45/0x6c
      	 [<ffffffff8100ae2b>] system_call_fastpath+0x16/0x1b
      
      The object state might also be OBJECT_DYING or OBJECT_WITHDRAWING.
      
      This should be handled by simply rejecting the new operation with ENOBUFS.
      There's no need to log an error for it.  Events of this type now appear in the
      stats file under Ops:rej.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      e3d4d28b
    • David Howells's avatar
      FS-Cache: Don't delete pending pages from the page-store tracking tree · 285e728b
      David Howells authored
      
      
      Don't delete pending pages from the page-store tracking tree, but rather send
      them for another write as they've presumably been updated.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      285e728b
    • David Howells's avatar
      FS-Cache: Fix lock misorder in fscache_write_op() · 1bccf513
      David Howells authored
      
      
      FS-Cache has two structs internally for keeping track of the internal state of
      a cached file: the fscache_cookie struct, which represents the netfs's state,
      and fscache_object struct, which represents the cache's state.  Each has a
      pointer that points to the other (when both are in existence), and each has a
      spinlock for pointer maintenance.
      
      Since netfs operations approach these structures from the cookie side, they get
      the cookie lock first, then the object lock.  Cache operations, on the other
      hand, approach from the object side, and get the object lock first.  It is not
      then permitted for a cache operation to get the cookie lock whilst it is
      holding the object lock lest deadlock occur; instead, it must do one of two
      things:
      
       (1) increment the cookie usage counter, drop the object lock and then get both
           locks in order, or
      
       (2) simply hold the object lock as certain parts of the cookie may not be
           altered whilst the object lock is held.
      
      It is also not permitted to follow either pointer without holding the lock at
      the end you start with.  To break the pointers between the cookie and the
      object, both locks must be held.
      
      fscache_write_op(), however, violates the locking rules: It attempts to get the
      cookie lock without (a) checking that the cookie pointer is a valid pointer,
      and (b) holding the object lock to protect the cookie pointer whilst it follows
      it.  This is so that it can access the pending page store tree without
      interference from __fscache_write_page().
      
      This is fixed by splitting the cookie lock, such that the page store tracking
      tree is protected by its own lock, and checking that the cookie pointer is
      non-NULL before we attempt to follow it whilst holding the object lock.
      
      The new lock is subordinate to both the cookie lock and the object lock, and so
      should be taken after those.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      1bccf513
    • David Howells's avatar
      FS-Cache: The object-available state can't rely on the cookie to be available · 6897e3df
      David Howells authored
      
      
      The object-available state in the object processing state machine (as
      processed by fscache_object_available()) can't rely on the cookie to be
      available because the FSCACHE_COOKIE_CREATING bit may have been cleared by
      fscache_obtained_object() prior to the object being put into the
      FSCACHE_OBJECT_AVAILABLE state.
      
      Clearing the FSCACHE_COOKIE_CREATING bit on a cookie permits
      __fscache_relinquish_cookie() to proceed and detach the cookie from the
      object.
      
      To deal with this, we don't dereference object->cookie in
      fscache_object_available() if the object has already been detached.
      
      In addition, a couple of assertions are added into fscache_drop_object() to
      make sure the object is unbound from the cookie before it gets there.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      6897e3df