1. 11 May, 2010 2 commits
    • David Howells's avatar
      CacheFiles: Fix occasional EIO on call to vfs_unlink() · c61ea31d
      David Howells authored
      Fix an occasional EIO returned by a call to vfs_unlink():
      
      	[ 4868.465413] CacheFiles: I/O Error: Unlink failed
      	[ 4868.465444] FS-Cache: Cache cachefiles stopped due to I/O error
      	[ 4947.320011] CacheFiles: File cache on md3 unregistering
      	[ 4947.320041] FS-Cache: Withdrawing cache "mycache"
      	[ 5127.348683] FS-Cache: Cache "mycache" added (type cachefiles)
      	[ 5127.348716] CacheFiles: File cache on md3 registered
      	[ 7076.871081] CacheFiles: I/O Error: Unlink failed
      	[ 7076.871130] FS-Cache: Cache cachefiles stopped due to I/O error
      	[ 7116.780891] CacheFiles: File cache on md3 unregistering
      	[ 7116.780937] FS-Cache: Withdrawing cache "mycache"
      	[ 7296.813394] FS-Cache: Cache "mycache" added (type cachefiles)
      	[ 7296.813432] CacheFiles: File cache on md3 registered
      
      What happens is this:
      
       (1) A cached NFS file is seen to have become out of date, so NFS retires the
           object and immediately acquires a new object with the same key.
      
       (2) Retirement of the old object is done asynchronously - so the lookup/create
           to generate the new object may be done first.
      
           This can be a problem as the old object and the new object must exist at
           the same point in the backing filesystem (i.e. they must have the same
           pathname).
      
       (3) The lookup for the new object sees that a backing file already exists,
           checks to see whether it is valid and sees that it isn't.  It then deletes
           that file and creates a new one on disk.
      
       (4) The retirement phase for the old file is then performed.  It tries to
           delete the dentry it has, but ext4_unlink() returns -EIO because the inode
           attached to that dentry no longer matches the inode number associated with
           the filename in the parent directory.
      
      The trace below shows this quite well.
      
      	[md5sum] ==> __fscache_relinquish_cookie(ffff88002d12fb58{NFS.fh,ffff88002ce62100},1)
      	[md5sum] ==> __fscache_acquire_cookie({NFS.server},{NFS.fh},ffff88002ce62100)
      
      NFS has retired the old cookie and asked for a new one.
      
      	[kslowd] ==> fscache_object_state_machine({OBJ52,OBJECT_ACTIVE,24})
      	[kslowd] <== fscache_object_state_machine() [->OBJECT_DYING]
      	[kslowd] ==> fscache_object_state_machine({OBJ53,OBJECT_INIT,0})
      	[kslowd] <== fscache_object_state_machine() [->OBJECT_LOOKING_UP]
      	[kslowd] ==> fscache_object_state_machine({OBJ52,OBJECT_DYING,24})
      	[kslowd] <== fscache_object_state_machine() [->OBJECT_RECYCLING]
      
      The old object (OBJ52) is going through the terminal states to get rid of it,
      whilst the new object - (OBJ53) - is coming into being.
      
      	[kslowd] ==> fscache_object_state_machine({OBJ53,OBJECT_LOOKING_UP,0})
      	[kslowd] ==> cachefiles_walk_to_object({ffff88003029d8b8},OBJ53,@68,)
      	[kslowd] lookup '@68'
      	[kslowd] next -> ffff88002ce41bd0 positive
      	[kslowd] advance
      	[kslowd] lookup 'Es0g00og0_Nd_XCYe3BOzvXrsBLMlN6aw16M1htaA'
      	[kslowd] next -> ffff8800369faac8 positive
      
      The new object has looked up the subdir in which the file would be in (getting
      dentry ffff88002ce41bd0) and then looked up the file itself (getting dentry
      ffff8800369faac8).
      
      	[kslowd] validate 'Es0g00og0_Nd_XCYe3BOzvXrsBLMlN6aw16M1htaA'
      	[kslowd] ==> cachefiles_bury_object(,'@68','Es0g00og0_Nd_XCYe3BOzvXrsBLMlN6aw16M1htaA')
      	[kslowd] remove ffff8800369faac8 from ffff88002ce41bd0
      	[kslowd] unlink stale object
      	[kslowd] <== cachefiles_bury_object() = 0
      
      It then checks the file's xattrs to see if it's valid.  NFS says that the
      auxiliary data indicate the file is out of date (obvious to us - that's why NFS
      ditched the old version and got a new one).  CacheFiles then deletes the old
      file (dentry ffff8800369faac8).
      
      	[kslowd] redo lookup
      	[kslowd] lookup 'Es0g00og0_Nd_XCYe3BOzvXrsBLMlN6aw16M1htaA'
      	[kslowd] next -> ffff88002cd94288 negative
      	[kslowd] create -> ffff88002cd94288{ffff88002cdaf238{ino=148247}}
      
      CacheFiles then redoes the lookup and gets a negative result in a new dentry
      (ffff88002cd94288) which it then creates a file for.
      
      	[kslowd] ==> cachefiles_mark_object_active(,OBJ53)
      	[kslowd] <== cachefiles_mark_object_active() = 0
      	[kslowd] === OBTAINED_OBJECT ===
      	[kslowd] <== cachefiles_walk_to_object() = 0 [148247]
      	[kslowd] <== fscache_object_state_machine() [->OBJECT_AVAILABLE]
      
      The new object is then marked active and the state machine moves to the
      available state - at which point NFS can start filling the object.
      
      	[kslowd] ==> fscache_object_state_machine({OBJ52,OBJECT_RECYCLING,20})
      	[kslowd] ==> fscache_release_object()
      	[kslowd] ==> cachefiles_drop_object({OBJ52,2})
      	[kslowd] ==> cachefiles_delete_object(,OBJ52{ffff8800369faac8})
      
      The old object, meanwhile, goes on with being retired.  If allocation occurs
      first, cachefiles_delete_object() has to wait for dir->d_inode->i_mutex to
      become available before it can continue.
      
      	[kslowd] ==> cachefiles_bury_object(,'@68','Es0g00og0_Nd_XCYe3BOzvXrsBLMlN6aw16M1htaA')
      	[kslowd] remove ffff8800369faac8 from ffff88002ce41bd0
      	[kslowd] unlink stale object
      	EXT4-fs warning (device sda6): ext4_unlink: Inode number mismatch in unlink (148247!=148193)
      	CacheFiles: I/O Error: Unlink failed
      	FS-Cache: Cache cachefiles stopped due to I/O error
      
      CacheFiles then tries to delete the file for the old object, but the dentry it
      has (ffff8800369faac8) no longer points to a valid inode for that directory
      entry, and so ext4_unlink() returns -EIO when de->inode does not match i_ino.
      
      	[kslowd] <== cachefiles_bury_object() = -5
      	[kslowd] <== cachefiles_delete_object() = -5
      	[kslowd] <== fscache_object_state_machine() [->OBJECT_DEAD]
      	[kslowd] ==> fscache_object_state_machine({OBJ53,OBJECT_AVAILABLE,0})
      	[kslowd] <== fscache_object_state_machine() [->OBJECT_ACTIVE]
      
      (Note that the above trace includes extra information beyond that produced by
      the upstream code).
      
      The fix is to note when an object that is being retired has had its object
      deleted preemptively by a replacement object that is being created, and to
      skip the second removal attempt in such a case.
      Reported-by: default avatarGreg M <gregm@servu.net.au>
      Reported-by: default avatarMark Moseley <moseleymark@gmail.com>
      Reported-by: default avatarRomain DEGEZ <romain.degez@smartjog.com>
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      c61ea31d
    • Alex Chiang's avatar
      ACPI: sleep: eliminate duplicate entries in acpisleep_dmi_table[] · 7d6fb7bd
      Alex Chiang authored
      Duplicate entries ended up acpisleep_dmi_table[] by accident.
      They don't hurt functionality, but they are ugly, so let's get
      rid of them.
      
      Cc: stable@kernel.org
      Signed-off-by: default avatarAlex Chiang <achiang@canonical.com>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      7d6fb7bd
  2. 10 May, 2010 8 commits
  3. 07 May, 2010 15 commits
  4. 06 May, 2010 15 commits