...as always, rename is the messiest of the bunch. We have to track
whether to retry or not via a separate flag since the error handling
is already quite complex.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

...so we can pass in LOOKUP_REVAL. For now, nothing does yet.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Where we can pass in LOOKUP_DIRECTORY or LOOKUP_REVAL. Any other flags
passed in here are currently ignored.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

This function is expected to be called from path-based syscalls to help
them decide whether to try the lookup and call again in the event that
they got an -ESTALE return back on an earier try.

Currently, we only retry the call once on an ESTALE error, but in the
event that we decide that that's not enough in the future, we should be
able to change the logic in this helper without too much effort.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Merge branch 'fscache' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs into for-linus

NFS appears to use d_obtain_alias() to create the root dentry rather than
d_make_root.  This can cause 'prepend_path()' to complain that the root
has a weird name if an NFS filesystem is lazily unmounted.  e.g.  if
"/mnt" is an NFS mount then

 { cd /mnt; umount -l /mnt ; ls -l /proc/self/cwd; }

will cause a WARN message like
   WARNING: at /home/git/linux/fs/dcache.c:2624 prepend_path+0x1d7/0x1e0()
   ...
   Root dentry has weird name <>

to appear in kernel logs.

So change d_obtain_alias() to use "/" rather than "" as the anonymous
name.
Signed-off-by: NeilBrown <neilb@suse.de>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Commit 8e22cc88 removes the (un)lock_super
function definitions but forgets to remove their prototypes.
Signed-off-by: Alessio Igor Bogani <abogani@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Removed vmtruncate
Signed-off-by: Marco Stornelli <marco.stornelli@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Removed vmtruncate
Signed-off-by: Marco Stornelli <marco.stornelli@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Removed vmtruncate
Signed-off-by: Marco Stornelli <marco.stornelli@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Removed vmtruncate
Signed-off-by: Marco Stornelli <marco.stornelli@gmail.com>
Reviewed-by: Anton Altaparmakov <anton@tuxera.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Removed vmtruncate
Signed-off-by: Marco Stornelli <marco.stornelli@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Removed vmtruncate
Signed-off-by: Marco Stornelli <marco.stornelli@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Removed vmtruncate
Signed-off-by: Marco Stornelli <marco.stornelli@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Removed vmtruncate
Signed-off-by: Marco Stornelli <marco.stornelli@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Removed vmtruncate
Signed-off-by: Marco Stornelli <marco.stornelli@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Removed vmtruncate
Signed-off-by: Marco Stornelli <marco.stornelli@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Removed vmtruncate
Signed-off-by: Marco Stornelli <marco.stornelli@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Provide fscache_cancel_op() with a pointer to a function it should invoke under
lock if it cancels an operation.

Use this to clear the remaining page count upon cancellation of a pending
retrieval operation so that fscache_release_retrieval_op() doesn't get an
assertion failure (see below).  This can happen when a signal occurs, say from
CTRL-C being pressed during data retrieval.

FS-Cache: Assertion failed
3 == 0 is false
------------[ cut here ]------------
kernel BUG at fs/fscache/page.c:237!
invalid opcode: 0000 [#641] SMP
Modules linked in: cachefiles(F) nfsv4(F) nfsv3(F) nfsv2(F) nfs(F) fscache(F) auth_rpcgss(F) nfs_acl(F) lockd(F) sunrpc(F)
CPU 0
Pid: 6075, comm: slurp-q Tainted: GF     D      3.7.0-rc8-fsdevel+ #411                  /DG965RY
RIP: 0010:[<ffffffffa007f328>]  [<ffffffffa007f328>] fscache_release_retrieval_op+0x75/0xff [fscache]
RSP: 0000:ffff88001c6d7988  EFLAGS: 00010296
RAX: 000000000000000f RBX: ffff880014cdfe00 RCX: ffffffff6c102000
RDX: ffffffff8102d1ad RSI: ffffffff6c102000 RDI: ffffffff8102d1d6
RBP: ffff88001c6d7998 R08: 0000000000000002 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 00000000fffffe00
R13: ffff88001c6d7ab4 R14: ffff88001a8638a0 R15: ffff88001552b190
FS:  00007f877aaf0700(0000) GS:ffff88003bc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 00007fff11378fd2 CR3: 000000001c6c6000 CR4: 00000000000007f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process slurp-q (pid: 6075, threadinfo ffff88001c6d6000, task ffff88001c6c4080)
Stack:
 ffffffffa007ec07 ffff880014cdfe00 ffff88001c6d79c8 ffffffffa007db4d
 ffffffffa007ec07 ffff880014cdfe00 00000000fffffe00 ffff88001c6d7ab4
 ffff88001c6d7a38 ffffffffa008116d 0000000000000000 ffff88001c6c4080
Call Trace:
 [<ffffffffa007ec07>] ? fscache_cancel_op+0x194/0x1cf [fscache]
 [<ffffffffa007db4d>] fscache_put_operation+0x135/0x2ed [fscache]
 [<ffffffffa007ec07>] ? fscache_cancel_op+0x194/0x1cf [fscache]
 [<ffffffffa008116d>] __fscache_read_or_alloc_pages+0x413/0x4bc [fscache]
 [<ffffffff810ac8ae>] ? __alloc_pages_nodemask+0x195/0x75c
 [<ffffffffa00aab0f>] __nfs_readpages_from_fscache+0x86/0x13d [nfs]
 [<ffffffffa00a5fe0>] nfs_readpages+0x186/0x1bd [nfs]
 [<ffffffff810d23c8>] ? alloc_pages_current+0xc7/0xe4
 [<ffffffff810a68b5>] ? __page_cache_alloc+0x84/0x91
 [<ffffffff810af912>] ? __do_page_cache_readahead+0xa6/0x2e0
 [<ffffffff810afaa3>] __do_page_cache_readahead+0x237/0x2e0
 [<ffffffff810af912>] ? __do_page_cache_readahead+0xa6/0x2e0
 [<ffffffff810afe3e>] ra_submit+0x1c/0x20
 [<ffffffff810b019b>] ondemand_readahead+0x359/0x382
 [<ffffffff810b0279>] page_cache_sync_readahead+0x38/0x3a
 [<ffffffff810a77b5>] generic_file_aio_read+0x26b/0x637
 [<ffffffffa00f1852>] ? nfs_mark_delegation_referenced+0xb/0xb [nfsv4]
 [<ffffffffa009cc85>] nfs_file_read+0xaa/0xcf [nfs]
 [<ffffffff810db5b3>] do_sync_read+0x91/0xd1
 [<ffffffff810dbb8b>] vfs_read+0x9b/0x144
 [<ffffffff810dbc78>] sys_read+0x44/0x75
 [<ffffffff81422892>] system_call_fastpath+0x16/0x1b
Signed-off-by: David Howells <dhowells@redhat.com>

Mark as cancelled an operation that is in progress rather than pending at the
time it is cancelled, and call fscache_complete_op() to cancel an operation so
that blocked ops can be started.
Signed-off-by: David Howells <dhowells@redhat.com>

In fscache_write_op(), if the object is determined to have become inactive or
to have lost its cookie, we don't move the operation state from in-progress,
and so an assertion in fscache_put_operation() fails with an assertion (see
below).

Instrumenting fscache_op_work_func() indicates that it called
fscache_write_op() before calling fscache_put_operation() - where the assertion
failed.  The assertion at line 433 indicates that the operation state is
IN_PROGRESS rather than being COMPLETE or CANCELLED.

Instrumenting fscache_write_op() showed that it was being called on an object
that had had its cookie removed and that this was due to relinquishment of the
cookie by the netfs.  At this point fscache no longer has access to the pages
of netfs data that were requested to be written, and so simply cancelling the
operation is the thing to do.

FS-Cache: Assertion failed
3 == 5 is false
------------[ cut here ]------------
kernel BUG at fs/fscache/operation.c:433!
invalid opcode: 0000 [#1] SMP
Modules linked in: cachefiles(F) nfsv4(F) nfsv3(F) nfsv2(F) nfs(F) fscache(F) auth_rpcgss(F) nfs_acl(F) lockd(F) sunrpc(F)
CPU 0
Pid: 1035, comm: kworker/u:3 Tainted: GF            3.7.0-rc8-fsdevel+ #411                  /DG965RY
RIP: 0010:[<ffffffffa007db22>]  [<ffffffffa007db22>] fscache_put_operation+0x11a/0x2ed [fscache]
RSP: 0018:ffff88003e32bcf8  EFLAGS: 00010296
RAX: 000000000000000f RBX: ffff88001818eb78 RCX: ffffffff6c102000
RDX: ffffffff8102d1ad RSI: ffffffff6c102000 RDI: ffffffff8102d1d6
RBP: ffff88003e32bd18 R08: 0000000000000002 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffffa00811da
R13: 0000000000000001 R14: 0000000100625d26 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88003bc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 00007fff7dd31c68 CR3: 000000003d730000 CR4: 00000000000007f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process kworker/u:3 (pid: 1035, threadinfo ffff88003e32a000, task ffff88003bb38080)
Stack:
 ffffffff8102d1ad ffff88001818eb78 ffffffffa00811da 0000000000000001
 ffff88003e32bd48 ffffffffa007f0ad ffff88001818eb78 ffffffff819583c0
 ffff88003df24e00 ffff88003882c3e0 ffff88003e32bde8 ffffffff81042de0
Call Trace:
 [<ffffffff8102d1ad>] ? vprintk_emit+0x3c6/0x41a
 [<ffffffffa00811da>] ? __fscache_read_or_alloc_pages+0x4bc/0x4bc [fscache]
 [<ffffffffa007f0ad>] fscache_op_work_func+0xec/0x123 [fscache]
 [<ffffffff81042de0>] process_one_work+0x21c/0x3b0
 [<ffffffff81042d82>] ? process_one_work+0x1be/0x3b0
 [<ffffffffa007efc1>] ? fscache_operation_gc+0x23e/0x23e [fscache]
 [<ffffffff8104332e>] worker_thread+0x202/0x2df
 [<ffffffff8104312c>] ? rescuer_thread+0x18e/0x18e
 [<ffffffff81047c1c>] kthread+0xd0/0xd8
 [<ffffffff81421bfa>] ? _raw_spin_unlock_irq+0x29/0x3e
 [<ffffffff81047b4c>] ? __init_kthread_worker+0x55/0x55
 [<ffffffff814227ec>] ret_from_fork+0x7c/0xb0
 [<ffffffff81047b4c>] ? __init_kthread_worker+0x55/0x55
Signed-off-by: David Howells <dhowells@redhat.com>

wait_on_bit() with TASK_INTERRUPTIBLE returns 1 rather than a negative error
code, so change what we check for.  This means that the signal handling in
fscache_wait_for_retrieval_activation()  should now work properly.

Without this, the following bug can be seen if CTRL-C is pressed during
fscache read operation:

FS-Cache: Assertion failed
2 == 3 is false
------------[ cut here ]------------
kernel BUG at fs/fscache/page.c:347!
invalid opcode: 0000 [#1] SMP
Modules linked in: cachefiles(F) nfsv4(F) nfsv3(F) nfsv2(F) nfs(F) fscache(F) auth_rpcgss(F) nfs_acl(F) lockd(F) sunrpc(F)
CPU 1
Pid: 15006, comm: slurp-q Tainted: GF            3.7.0-rc8-fsdevel+ #411                  /DG965RY
RIP: 0010:[<ffffffffa007fcb4>]  [<ffffffffa007fcb4>] fscache_wait_for_retrieval_activation+0x167/0x177 [fscache]
RSP: 0018:ffff88002a4c39a8  EFLAGS: 00010292
RAX: 000000000000001a RBX: ffff88002d3dc158 RCX: 0000000000008685
RDX: ffffffff8102ccd6 RSI: 0000000000000001 RDI: ffffffff8102d1d6
RBP: ffff88002a4c39c8 R08: 0000000000000002 R09: 0000000000000000
R10: ffffffff8163afa0 R11: ffff88003bd11900 R12: ffffffffa00868c8
R13: ffff880028306458 R14: ffff88002d3dc1b0 R15: ffff88001372e538
FS:  00007f17426a0700(0000) GS:ffff88003bd00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 00007f1742494a44 CR3: 0000000031bd7000 CR4: 00000000000007e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process slurp-q (pid: 15006, threadinfo ffff88002a4c2000, task ffff880023de3040)
Stack:
 ffff88002d3dc158 ffff88001372e538 ffff88002a4c3ab4 ffff8800283064e0
 ffff88002a4c3a38 ffffffffa0080f6d 0000000000000000 ffff880023de3040
 ffff88002a4c3ac8 ffffffff810ac8ae ffff880028306458 ffff88002a4c3bc8
Call Trace:
 [<ffffffffa0080f6d>] __fscache_read_or_alloc_pages+0x24f/0x4bc [fscache]
 [<ffffffff810ac8ae>] ? __alloc_pages_nodemask+0x195/0x75c
 [<ffffffffa00aab0f>] __nfs_readpages_from_fscache+0x86/0x13d [nfs]
 [<ffffffffa00a5fe0>] nfs_readpages+0x186/0x1bd [nfs]
 [<ffffffff810d23c8>] ? alloc_pages_current+0xc7/0xe4
 [<ffffffff810a68b5>] ? __page_cache_alloc+0x84/0x91
 [<ffffffff810af912>] ? __do_page_cache_readahead+0xa6/0x2e0
 [<ffffffff810afaa3>] __do_page_cache_readahead+0x237/0x2e0
 [<ffffffff810af912>] ? __do_page_cache_readahead+0xa6/0x2e0
 [<ffffffff810afe3e>] ra_submit+0x1c/0x20
 [<ffffffff810b019b>] ondemand_readahead+0x359/0x382
 [<ffffffff810b0279>] page_cache_sync_readahead+0x38/0x3a
 [<ffffffff810a77b5>] generic_file_aio_read+0x26b/0x637
 [<ffffffffa00f1852>] ? nfs_mark_delegation_referenced+0xb/0xb [nfsv4]
 [<ffffffffa009cc85>] nfs_file_read+0xaa/0xcf [nfs]
 [<ffffffff810db5b3>] do_sync_read+0x91/0xd1
 [<ffffffff810dbb8b>] vfs_read+0x9b/0x144
 [<ffffffff810dbc78>] sys_read+0x44/0x75
 [<ffffffff81422892>] system_call_fastpath+0x16/0x1b
Signed-off-by: David Howells <dhowells@redhat.com>

nfs4_file_open() should open files for fscaching.
Signed-off-by: David Howells <dhowells@redhat.com>

Add a missing transition to the FS-Cache object state machine to handle an
invalidation event occuring between the back end completing the object lookup
by calling fscache_obtained_object() (which moves to state OBJECT_AVAILABLE)
and the backend returning to fscache_lookup_object() and thence to
fscache_object_state_machine() which then does a goto lookup_transit to handle
the transition - but lookup_transit doesn't handle EV_INVALIDATE.

Without this, the following BUG can be logged:

	FS-Cache: Unsupported event 2 [5/f7] in state OBJECT_AVAILABLE
	------------[ cut here ]------------
	kernel BUG at fs/fscache/object.c:357!

Where event 2 is EV_INVALIDATE.
Signed-off-by: David Howells <dhowells@redhat.com>

nfs_migrate_page() does not wait for FS-Cache to finish with a page, probably
leading to the following bad-page-state:

 BUG: Bad page state in process python-bin  pfn:17d39b
 page:ffffea00053649e8 flags:004000000000100c count:0 mapcount:0 mapping:(null)
index:38686 (Tainted: G    B      ---------------- )
 Pid: 31053, comm: python-bin Tainted: G    B      ----------------
2.6.32-71.24.1.el6.x86_64 #1
 Call Trace:
 [<ffffffff8111bfe7>] bad_page+0x107/0x160
 [<ffffffff8111ee69>] free_hot_cold_page+0x1c9/0x220
 [<ffffffff8111ef19>] __pagevec_free+0x59/0xb0
 [<ffffffff8104b988>] ? flush_tlb_others_ipi+0x128/0x130
 [<ffffffff8112230c>] release_pages+0x21c/0x250
 [<ffffffff8115b92a>] ? remove_migration_pte+0x28a/0x2b0
 [<ffffffff8115f3f8>] ? mem_cgroup_get_reclaim_stat_from_page+0x18/0x70
 [<ffffffff81122687>] ____pagevec_lru_add+0x167/0x180
 [<ffffffff811226f8>] __lru_cache_add+0x58/0x70
 [<ffffffff81122731>] lru_cache_add_lru+0x21/0x40
 [<ffffffff81123f49>] putback_lru_page+0x69/0x100
 [<ffffffff8115c0bd>] migrate_pages+0x13d/0x5d0
 [<ffffffff81122687>] ? ____pagevec_lru_add+0x167/0x180
 [<ffffffff81152ab0>] ? compaction_alloc+0x0/0x370
 [<ffffffff8115255c>] compact_zone+0x4cc/0x600
 [<ffffffff8111cfac>] ? get_page_from_freelist+0x15c/0x820
 [<ffffffff810672f4>] ? check_preempt_wakeup+0x1c4/0x3c0
 [<ffffffff8115290e>] compact_zone_order+0x7e/0xb0
 [<ffffffff81152a49>] try_to_compact_pages+0x109/0x170
 [<ffffffff8111e94d>] __alloc_pages_nodemask+0x5ed/0x850
 [<ffffffff814c9136>] ? thread_return+0x4e/0x778
 [<ffffffff81150d43>] alloc_pages_vma+0x93/0x150
 [<ffffffff81167ea5>] do_huge_pmd_anonymous_page+0x135/0x340
 [<ffffffff814cb6f6>] ? rwsem_down_read_failed+0x26/0x30
 [<ffffffff81136755>] handle_mm_fault+0x245/0x2b0
 [<ffffffff814ce383>] do_page_fault+0x123/0x3a0
 [<ffffffff814cbdf5>] page_fault+0x25/0x30

nfs_migrate_page() calls nfs_fscache_release_page() which doesn't actually wait
- even if __GFP_WAIT is set.  The reason that doesn't wait is that
fscache_maybe_release_page() might deadlock the allocator as the work threads
writing to the cache may all end up sleeping on memory allocation.

However, I wonder if that is actually a problem.  There are a number of things
I can do to deal with this:

 (1) Make nfs_migrate_page() wait.

 (2) Make fscache_maybe_release_page() honour the __GFP_WAIT flag.

 (3) Set a timeout around the wait.

 (4) Make nfs_migrate_page() return an error if the page is still busy.

For the moment, I'll select (2) and (4).
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Jeff Layton <jlayton@redhat.com>

The function to submit an exclusive op (fscache_submit_exclusive_op()) can BUG
if there's been an I/O error because it may see the parent cache object in an
unexpected state.  It should only BUG if there hasn't been an I/O error.

In this case the problem was produced by remounting the cache partition to be
R/O.  The EROFS state was detected and the cache was aborted, but not
everything handled the aborting correctly.

SysRq : Emergency Remount R/O
EXT4-fs (sda6): re-mounted. Opts: (null)
Emergency Remount complete
CacheFiles: I/O Error: Failed to update xattr with error -30
FS-Cache: Cache cachefiles stopped due to I/O error
------------[ cut here ]------------
kernel BUG at fs/fscache/operation.c:128!
invalid opcode: 0000 [#1] SMP 
CPU 0 
Modules linked in: cachefiles nfs fscache auth_rpcgss nfs_acl lockd sunrpc

Pid: 6612, comm: kworker/u:2 Not tainted 3.1.0-rc8-fsdevel+ #1093                  /DG965RY
RIP: 0010:[<ffffffffa00739c0>]  [<ffffffffa00739c0>] fscache_submit_exclusive_op+0x2ad/0x2c2 [fscache]
RSP: 0018:ffff880000853d40  EFLAGS: 00010206
RAX: ffff880038ac72a8 RBX: ffff8800181f2260 RCX: ffffffff81f2b2b0
RDX: 0000000000000001 RSI: ffffffff8179a478 RDI: ffff8800181f2280
RBP: ffff880000853d60 R08: 0000000000000002 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: ffff880038ac7268
R13: ffff8800181f2280 R14: ffff88003a359190 R15: 000000010122b162
FS:  0000000000000000(0000) GS:ffff88003bc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 00000034cc4a77f0 CR3: 0000000010e96000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process kworker/u:2 (pid: 6612, threadinfo ffff880000852000, task ffff880014c3c040)
Stack:
 ffff8800181f2260 ffff8800181f2310 ffff880038ac7268 ffff8800181f2260
 ffff880000853dc0 ffffffffa0072375 ffff880037ecfe00 ffff88003a359198
 ffff880000853dc0 0000000000000246 0000000000000000 ffff88000a91d308
Call Trace:
 [<ffffffffa0072375>] fscache_object_work_func+0x792/0xe65 [fscache]
 [<ffffffff81047e44>] process_one_work+0x1eb/0x37f
 [<ffffffff81047de6>] ? process_one_work+0x18d/0x37f
 [<ffffffffa0071be3>] ? fscache_enqueue_dependents+0xd8/0xd8 [fscache]
 [<ffffffff810482e4>] worker_thread+0x15a/0x21a
 [<ffffffff8104818a>] ? rescuer_thread+0x188/0x188
 [<ffffffff8104bf96>] kthread+0x7f/0x87
 [<ffffffff813ad6f4>] kernel_thread_helper+0x4/0x10
 [<ffffffff81026b98>] ? finish_task_switch+0x45/0xc0
 [<ffffffff813abd1d>] ? retint_restore_args+0xe/0xe
 [<ffffffff8104bf17>] ? __init_kthread_worker+0x53/0x53
 [<ffffffff813ad6f0>] ? gs_change+0xb/0xb
Signed-off-by: David Howells <dhowells@redhat.com>

Limit the number of I/O error reports for a cache to 1 to prevent massive
amounts of noise.  After the first I/O error the cache is taken off line
automatically, so must be restarted to resume caching.
Signed-off-by: David Howells <dhowells@redhat.com>

Don't mask off the object event mask when printing it.  That way it can be seen
if threre are bits set that shouldn't be.
Signed-off-by: David Howells <dhowells@redhat.com>

Initialise the object event mask with the calculated mask rather than unmasking
undefined events also.
Signed-off-by: David Howells <dhowells@redhat.com>

Convert the fscache_object event IDs from #defines into an enum.  Also add an
extra label to the enum to carry the event count and redefine the event mask
in terms of that.
Signed-off-by: David Howells <dhowells@redhat.com>

CacheFiles is missing some calls to fscache_retrieval_complete() in the error
handling/collision paths of its reader functions.

This can be seen by the following assertion tripping in fscache_put_operation()
whereby the operation being destroyed is still in the in-progress state and has
not been cancelled or completed:

FS-Cache: Assertion failed
3 == 5 is false
------------[ cut here ]------------
kernel BUG at fs/fscache/operation.c:408!
invalid opcode: 0000 [#1] SMP
CPU 2
Modules linked in: xfs ioatdma dca loop joydev evdev
psmouse dcdbas pcspkr serio_raw i5000_edac edac_core i5k_amb shpchp
pci_hotplug sg sr_mod]

Pid: 8062, comm: httpd Not tainted 3.1.0-rc8 #1 Dell Inc. PowerEdge 1950/0DT097
RIP: 0010:[<ffffffff81197b24>]  [<ffffffff81197b24>] fscache_put_operation+0x304/0x330
RSP: 0018:ffff880062f739d8  EFLAGS: 00010296
RAX: 0000000000000025 RBX: ffff8800c5122e84 RCX: ffffffff81ddf040
RDX: 00000000ffffffff RSI: 0000000000000082 RDI: ffffffff81ddef30
RBP: ffff880062f739f8 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000003 R12: ffff8800c5122e40
R13: ffff880037a2cd20 R14: ffff880087c7a058 R15: ffff880087c7a000
FS:  00007f63dcf636e0(0000) GS:ffff88022fc80000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0c0a91f000 CR3: 0000000062ec2000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process httpd (pid: 8062, threadinfo ffff880062f72000, task ffff880087e58000)
Stack:
 ffff880062f73bf8 0000000000000000 ffff880062f73bf8 ffff880037a2cd20
 ffff880062f73a68 ffffffff8119aa7e ffff88006540e000 ffff880062f73ad4
 ffff88008e9a4308 ffff880037a2cd20 ffff880062f73a48 ffff8800c5122e40
Call Trace:
 [<ffffffff8119aa7e>] __fscache_read_or_alloc_pages+0x1fe/0x530
 [<ffffffff81250780>] __nfs_readpages_from_fscache+0x70/0x1c0
 [<ffffffff8123142a>] nfs_readpages+0xca/0x1e0
 [<ffffffff815f3c06>] ? rpc_do_put_task+0x36/0x50
 [<ffffffff8122755b>] ? alloc_nfs_open_context+0x4b/0x110
 [<ffffffff815ecd1a>] ? rpc_call_sync+0x5a/0x70
 [<ffffffff810e7e9a>] __do_page_cache_readahead+0x1ca/0x270
 [<ffffffff810e7f61>] ra_submit+0x21/0x30
 [<ffffffff810e818d>] ondemand_readahead+0x11d/0x250
 [<ffffffff810e83b6>] page_cache_sync_readahead+0x36/0x60
 [<ffffffff810dffa4>] generic_file_aio_read+0x454/0x770
 [<ffffffff81224ce1>] nfs_file_read+0xe1/0x130
 [<ffffffff81121bd9>] do_sync_read+0xd9/0x120
 [<ffffffff8114088f>] ? mntput+0x1f/0x40
 [<ffffffff811238cb>] ? fput+0x1cb/0x260
 [<ffffffff81122938>] vfs_read+0xc8/0x180
 [<ffffffff81122af5>] sys_read+0x55/0x90
Reported-by: Mark Moseley <moseleymark@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>

Use the new FS-Cache invalidation facility from NFS to deal with foreign
changes being detected on the server rather than attempting to retire the old
cookie and get a new one.

The problem with the old method was that NFS did not wait for all outstanding
storage and retrieval ops on the cache to complete.  There was no automatic
wait between the calls to ->readpages() and calls to invalidate_inode_pages2()
as the latter can only wait on locked pages that have been added to the
pagecache (which they haven't yet on entry to ->readpages()).

This was leading to oopses like the one below when an outstanding read got cut
off from its cookie by a premature release.

BUG: unable to handle kernel NULL pointer dereference at 00000000000000a8
IP: [<ffffffffa0075118>] __fscache_read_or_alloc_pages+0x1dd/0x315 [fscache]
PGD 15889067 PUD 15890067 PMD 0
Oops: 0000 [#1] SMP
CPU 0
Modules linked in: cachefiles nfs fscache auth_rpcgss nfs_acl lockd sunrpc

Pid: 4544, comm: tar Not tainted 3.1.0-rc4-fsdevel+ #1064                  /DG965RY
RIP: 0010:[<ffffffffa0075118>]  [<ffffffffa0075118>] __fscache_read_or_alloc_pages+0x1dd/0x315 [fscache]
RSP: 0018:ffff8800158799e8  EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8800070d41e0 RCX: ffff8800083dc1b0
RDX: 0000000000000000 RSI: ffff880015879960 RDI: ffff88003e627b90
RBP: ffff880015879a28 R08: 0000000000000002 R09: 0000000000000002
R10: 0000000000000001 R11: ffff880015879950 R12: ffff880015879aa4
R13: 0000000000000000 R14: ffff8800083dc158 R15: ffff880015879be8
FS:  00007f671e9d87c0(0000) GS:ffff88003bc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 00000000000000a8 CR3: 000000001587f000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process tar (pid: 4544, threadinfo ffff880015878000, task ffff880015875040)
Stack:
 ffffffffa00b1759 ffff8800070dc158 ffff8800000213da ffff88002a286508
 ffff880015879aa4 ffff880015879be8 0000000000000001 ffff88002a2866e8
 ffff880015879a88 ffffffffa00b20be 00000000000200da ffff880015875040
Call Trace:
 [<ffffffffa00b1759>] ? nfs_fscache_wait_bit+0xd/0xd [nfs]
 [<ffffffffa00b20be>] __nfs_readpages_from_fscache+0x7e/0x13f [nfs]
 [<ffffffff81095fe7>] ? __alloc_pages_nodemask+0x156/0x662
 [<ffffffffa0098763>] nfs_readpages+0xee/0x187 [nfs]
 [<ffffffff81098a5e>] __do_page_cache_readahead+0x1be/0x267
 [<ffffffff81098942>] ? __do_page_cache_readahead+0xa2/0x267
 [<ffffffff81098d7b>] ra_submit+0x1c/0x20
 [<ffffffff8109900a>] ondemand_readahead+0x28b/0x29a
 [<ffffffff810990ce>] page_cache_sync_readahead+0x38/0x3a
 [<ffffffff81091d8a>] generic_file_aio_read+0x2ab/0x67e
 [<ffffffffa008cfbe>] nfs_file_read+0xa4/0xc9 [nfs]
 [<ffffffff810c22c4>] do_sync_read+0xba/0xfa
 [<ffffffff810a62c9>] ? might_fault+0x4e/0x9e
 [<ffffffff81177a47>] ? security_file_permission+0x7b/0x84
 [<ffffffff810c25dd>] ? rw_verify_area+0xab/0xc8
 [<ffffffff810c29a4>] vfs_read+0xaa/0x13a
 [<ffffffff810c2a79>] sys_read+0x45/0x6c
 [<ffffffff813ac37b>] system_call_fastpath+0x16/0x1b
Reported-by: Mark Moseley <moseleymark@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>