Commit Graph

381 Commits

Author SHA1 Message Date
Al Viro 884be17535 nfs: per-name sillyunlink exclusion
use d_alloc_parallel() for sillyunlink/lookup exclusion and
explicit rwsem (nfs_rmdir() being a writer and nfs_call_unlink() -
a reader) for rmdir/sillyunlink one.

That ought to make lookup/readdir/!O_CREAT atomic_open really
parallel on NFS.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-09 11:39:45 -04:00
Al Viro 9ac3d3e846 nfs: switch to ->iterate_shared()
aside of the usual care about seeding dcache from readdir, we need
to be careful about the pagecache evictions here.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-02 19:51:53 -04:00
Linus Torvalds 93061f390f These changes contains a fix for overlayfs interacting with some
(badly behaved) dentry code in various file systems.  These have been
 reviewed by Al and the respective file system mtinainers and are going
 through the ext4 tree for convenience.
 
 This also has a few ext4 encryption bug fixes that were discovered in
 Android testing (yes, we will need to get these sync'ed up with the
 fs/crypto code; I'll take care of that).  It also has some bug fixes
 and a change to ignore the legacy quota options to allow for xfstests
 regression testing of ext4's internal quota feature and to be more
 consistent with how xfs handles this case.
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Merge tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

Pull ext4 bugfixes from Ted Ts'o:
 "These changes contains a fix for overlayfs interacting with some
  (badly behaved) dentry code in various file systems.  These have been
  reviewed by Al and the respective file system mtinainers and are going
  through the ext4 tree for convenience.

  This also has a few ext4 encryption bug fixes that were discovered in
  Android testing (yes, we will need to get these sync'ed up with the
  fs/crypto code; I'll take care of that).  It also has some bug fixes
  and a change to ignore the legacy quota options to allow for xfstests
  regression testing of ext4's internal quota feature and to be more
  consistent with how xfs handles this case"

* tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: ignore quota mount options if the quota feature is enabled
  ext4 crypto: fix some error handling
  ext4: avoid calling dquot_get_next_id() if quota is not enabled
  ext4: retry block allocation for failed DIO and DAX writes
  ext4: add lockdep annotations for i_data_sem
  ext4: allow readdir()'s of large empty directories to be interrupted
  btrfs: fix crash/invalid memory access on fsync when using overlayfs
  ext4 crypto: use dget_parent() in ext4_d_revalidate()
  ext4: use file_dentry()
  ext4: use dget_parent() in ext4_file_open()
  nfs: use file_dentry()
  fs: add file_dentry()
  ext4 crypto: don't let data integrity writebacks fail with ENOMEM
  ext4: check if in-inode xattr is corrupted in ext4_expand_extra_isize_ea()
2016-04-07 17:22:20 -07:00
Kirill A. Shutemov 09cbfeaf1a mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros
PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time
ago with promise that one day it will be possible to implement page
cache with bigger chunks than PAGE_SIZE.

This promise never materialized.  And unlikely will.

We have many places where PAGE_CACHE_SIZE assumed to be equal to
PAGE_SIZE.  And it's constant source of confusion on whether
PAGE_CACHE_* or PAGE_* constant should be used in a particular case,
especially on the border between fs and mm.

Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much
breakage to be doable.

Let's stop pretending that pages in page cache are special.  They are
not.

The changes are pretty straight-forward:

 - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;

 - <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;

 - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN};

 - page_cache_get() -> get_page();

 - page_cache_release() -> put_page();

This patch contains automated changes generated with coccinelle using
script below.  For some reason, coccinelle doesn't patch header files.
I've called spatch for them manually.

The only adjustment after coccinelle is revert of changes to
PAGE_CAHCE_ALIGN definition: we are going to drop it later.

There are few places in the code where coccinelle didn't reach.  I'll
fix them manually in a separate patch.  Comments and documentation also
will be addressed with the separate patch.

virtual patch

@@
expression E;
@@
- E << (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E

@@
expression E;
@@
- E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E

@@
@@
- PAGE_CACHE_SHIFT
+ PAGE_SHIFT

@@
@@
- PAGE_CACHE_SIZE
+ PAGE_SIZE

@@
@@
- PAGE_CACHE_MASK
+ PAGE_MASK

@@
expression E;
@@
- PAGE_CACHE_ALIGN(E)
+ PAGE_ALIGN(E)

@@
expression E;
@@
- page_cache_get(E)
+ get_page(E)

@@
expression E;
@@
- page_cache_release(E)
+ put_page(E)

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-04 10:41:08 -07:00
Miklos Szeredi be62a1a8fd nfs: use file_dentry()
NFS may be used as lower layer of overlayfs and accessing f_path.dentry can
lead to a crash.

Fix by replacing direct access of file->f_path.dentry with the
file_dentry() accessor, which will always return a native object.

Fixes: 4bacc9c923 ("overlayfs: Make f_path always point to the overlay and f_inode to the underlay")
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Tested-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Acked-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: <stable@vger.kernel.org> # v4.2
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
2016-03-26 16:14:39 -04:00
Al Viro 130f9ab75d nfs_lookup: don't bother with d_instantiate(dentry, NULL)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-03-14 00:16:40 -04:00
Al Viro 5955102c99 wrappers for ->i_mutex access
parallel to mutex_{lock,unlock,trylock,is_locked,lock_nested},
inode_foo(inode) being mutex_foo(&inode->i_mutex).

Please, use those for access to ->i_mutex; over the coming cycle
->i_mutex will become rwsem, with ->lookup() done with it held
only shared.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-01-22 18:04:28 -05:00
Linus Torvalds 75f26df6ae NFS client updates for Linux 4.5
Highlights include:
 
 Stable fixes:
 - Fix a regression in the SunRPC socket polling code
 - Fix the attribute cache revalidation code
 - Fix race in __update_open_stateid()
 - Fix an lo->plh_block_lgets imbalance in layoutreturn
 - Fix an Oopsable typo in ff_mirror_match_fh()
 
 Features:
 - pNFS layout recall performance improvements.
 - pNFS/flexfiles: Support server-supplied layoutstats sampling period
 
 Bugfixes + cleanups:
 - NFSv4: Don't perform cached access checks before we've OPENed the file
 - Fix starvation issues with background flushes
 - Reclaim writes should be flushed as unstable writes if there are already
   entries in the commit lists
 - Various bugfixes from Chuck to fix NFS/RDMA send queue ordering problems
 - Ensure that we propagate fatal layoutget errors back to the application
 - Fixes for sundry flexfiles layoutstats bugs
 - Fix files/flexfiles to not cache invalidated layouts in the DS commit buckets
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Merge tag 'nfs-for-4.5-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs

Pull NFS client updates from Trond Myklebust:
 "Highlights include:

  Stable fixes:
   - Fix a regression in the SunRPC socket polling code
   - Fix the attribute cache revalidation code
   - Fix race in __update_open_stateid()
   - Fix an lo->plh_block_lgets imbalance in layoutreturn
   - Fix an Oopsable typo in ff_mirror_match_fh()

  Features:
   - pNFS layout recall performance improvements.
   - pNFS/flexfiles: Support server-supplied layoutstats sampling period

  Bugfixes + cleanups:
   - NFSv4: Don't perform cached access checks before we've OPENed the
     file
   - Fix starvation issues with background flushes
   - Reclaim writes should be flushed as unstable writes if there are
     already entries in the commit lists
   - Various bugfixes from Chuck to fix NFS/RDMA send queue ordering
     problems
   - Ensure that we propagate fatal layoutget errors back to the
     application
   - Fixes for sundry flexfiles layoutstats bugs
   - Fix files/flexfiles to not cache invalidated layouts in the DS
     commit buckets"

* tag 'nfs-for-4.5-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs: (68 commits)
  NFS: Fix a compile warning about unused variable in nfs_generic_pg_pgios()
  NFSv4: Fix a compile warning about no prototype for nfs4_ioctl()
  NFS: Use wait_on_atomic_t() for unlock after readahead
  SUNRPC: Fixup socket wait for memory
  NFSv4.1/pNFS: Cleanup constify struct pnfs_layout_range arguments
  NFSv4.1/pnfs: Cleanup copying of pnfs_layout_range structures
  NFSv4.1/pNFS: Cleanup pnfs_mark_matching_lsegs_invalid()
  NFSv4.1/pNFS: Fix a race in initiate_file_draining()
  NFSv4.1/pNFS: pnfs_error_mark_layout_for_return() must always return layout
  NFSv4.1/pNFS: pnfs_mark_matching_lsegs_return() should set the iomode
  NFSv4.1/pNFS: Use nfs4_stateid_copy for copying stateids
  NFSv4.1/pNFS: Don't pass stateids by value to pnfs_send_layoutreturn()
  NFS: Relax requirements in nfs_flush_incompatible
  NFSv4.1/pNFS: Don't queue up a new commit if the layout segment is invalid
  NFS: Allow multiple commit requests in flight per file
  NFS/pNFS: Fix up pNFS write reschedule layering violations and bugs
  SUNRPC: Fix a missing break in rpc_anyaddr()
  pNFS/flexfiles: Fix an Oopsable typo in ff_mirror_match_fh()
  NFS: Fix attribute cache revalidation
  NFS: Ensure we revalidate attributes before using execute_ok()
  ...
2016-01-14 16:08:23 -08:00
Al Viro e8ecde25f5 Make sure that highmem pages are not added to symlink page cache
inode_nohighmem() is sufficient to make sure that page_get_link()
won't try to allocate a highmem page.  Moreover, it is sufficient
to make sure that page_symlink/__page_symlink won't do the same
thing.  However, any filesystem that manually preseeds the symlink's
page cache upon symlink(2) needs to make sure that the page it
inserts there won't be a highmem one.

Fortunately, only nfs and shmem have run afoul of that...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-01-14 17:56:54 -05:00
Trond Myklebust 5c5fc09a11 NFS: Ensure we revalidate attributes before using execute_ok()
Donald Buczek reports that NFS clients can also report incorrect
results for access() due to lack of revalidation of attributes
before calling execute_ok().
Looking closely, it seems chdir() is afflicted with the same problem.

Fix is to ensure we call nfs_revalidate_inode_rcu() or
nfs_revalidate_inode() as appropriate before deciding to trust
execute_ok().

Reported-by: Donald Buczek <buczek@molgen.mpg.de>
Link: http://lkml.kernel.org/r/1451331530-3748-1-git-send-email-buczek@molgen.mpg.de
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-12-28 19:37:05 -05:00
Trond Myklebust 762674f86d NFSv4: Don't perform cached access checks before we've OPENed the file
Donald Buczek reports that a nfs4 client incorrectly denies
execute access based on outdated file mode (missing 'x' bit).
After the mode on the server is 'fixed' (chmod +x) further execution
attempts continue to fail, because the nfs ACCESS call updates
the access parameter but not the mode parameter or the mode in
the inode.

The root cause is ultimately that the VFS is calling may_open()
before the NFS client has a chance to OPEN the file and hence revalidate
the access and attribute caches.

Al Viro suggests:
>>> Make nfs_permission() relax the checks when it sees MAY_OPEN, if you know
>>> that things will be caught by server anyway?
>>
>> That can work as long as we're guaranteed that everything that calls
>> inode_permission() with MAY_OPEN on a regular file will also follow up
>> with a vfs_open() or dentry_open() on success. Is this always the
>> case?
>
> 1) in do_tmpfile(), followed by do_dentry_open() (not reachable by NFS since
> it doesn't have ->tmpfile() instance anyway)
>
> 2) in atomic_open(), after the call of ->atomic_open() has succeeded.
>
> 3) in do_last(), followed on success by vfs_open()
>
> That's all.  All calls of inode_permission() that get MAY_OPEN come from
> may_open(), and there's no other callers of that puppy.

Reported-by: Donald Buczek <buczek@molgen.mpg.de>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=109771
Link: http://lkml.kernel.org/r/1451046656-26319-1-git-send-email-buczek@molgen.mpg.de
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-12-28 13:22:20 -05:00
Yaowei Bai 118c916356 fs/nfs: remove unnecessary new_valid_dev check
As new_valid_dev always returns 1, so !new_valid_dev check is not
needed, remove it.

Signed-off-by: Yaowei Bai <bywxiaobai@163.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-11-03 12:31:34 -05:00
Anna Schumaker c7e9668e78 NFS: Rename nfs_readdir_free_pagearray() and nfs_readdir_large_page()
nfs_readdir_xdr_to_array() uses both a cache array and an array of
pages, so I rename these functions to make it clearer how the code
works.  nfs_readdir_large_page() becomes nfs_readdir_alloc_pages()
because this function has absolutely nothing to do with setting up a
large page.  nfs_readdir_free_pagearray() becomes
nfs_readdir_free_pages() to stay consistent with the new alloc_pages()
function.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-08-17 13:29:31 -05:00
Anna Schumaker 0b936e37df NFS: Remove unused variable "pages_ptr"
This variable is initialized to NULL and is never modified before being
passed to nfs_readdir_free_large_page().  But that's okay, because
nfs_readdir_free_large_page() only seems to exist as a way of calling
nfs_readdir_free_pagearray() without this parameter.  Let's simplify by
removing pages_ptr and nfs_readdir_free_pagearray().

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-08-17 13:29:24 -05:00
Linus Torvalds 1dc51b8288 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull more vfs updates from Al Viro:
 "Assorted VFS fixes and related cleanups (IMO the most interesting in
  that part are f_path-related things and Eric's descriptor-related
  stuff).  UFS regression fixes (it got broken last cycle).  9P fixes.
  fs-cache series, DAX patches, Jan's file_remove_suid() work"

[ I'd say this is much more than "fixes and related cleanups".  The
  file_table locking rule change by Eric Dumazet is a rather big and
  fundamental update even if the patch isn't huge.   - Linus ]

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (49 commits)
  9p: cope with bogus responses from server in p9_client_{read,write}
  p9_client_write(): avoid double p9_free_req()
  9p: forgetting to cancel request on interrupted zero-copy RPC
  dax: bdev_direct_access() may sleep
  block: Add support for DAX reads/writes to block devices
  dax: Use copy_from_iter_nocache
  dax: Add block size note to documentation
  fs/file.c: __fget() and dup2() atomicity rules
  fs/file.c: don't acquire files->file_lock in fd_install()
  fs:super:get_anon_bdev: fix race condition could cause dev exceed its upper limitation
  vfs: avoid creation of inode number 0 in get_next_ino
  namei: make set_root_rcu() return void
  make simple_positive() public
  ufs: use dir_pages instead of ufs_dir_pages()
  pagemap.h: move dir_pages() over there
  remove the pointless include of lglock.h
  fs: cleanup slight list_entry abuse
  xfs: Correctly lock inode when removing suid and file capabilities
  fs: Call security_ops->inode_killpriv on truncate
  fs: Provide function telling whether file_remove_privs() will do anything
  ...
2015-07-04 19:36:06 -07:00
Kinglong Mee 2785110d2e nfs: Don't setting FILE_CREATED flags always
Commit 5bc2afc2b5 "NFSv4: Honour the 'opened' parameter in the atomic_open()
 filesystem method" have support the opened arguments now.

Also,
Commit 03da633aa7 "atomic_open: take care of EEXIST in no-open case with
 O_CREAT|O_EXCL in fs/namei.c" have change vfs's logical.

Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-07-01 11:30:21 -04:00
Al Viro dc3f4198ea make simple_positive() public
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-06-23 18:02:01 -04:00
Linus Torvalds 59953fba87 NFS client updates for Linux 4.1
Highlights include:
 
 Stable patches:
 - Fix a regression in /proc/self/mountstats
 - Fix the pNFS flexfiles O_DIRECT support
 - Fix high load average due to callback thread sleeping
 
 Bugfixes:
 - Various patches to fix the pNFS layoutcommit support
 - Do not cache pNFS deviceids unless server notifications are enabled
 - Fix a SUNRPC transport reconnection regression
 - make debugfs file creation failure non-fatal in SUNRPC
 - Another fix for circular directory warnings on NFSv4 "junctioned" mountpoints
 - Fix locking around NFSv4.2 fallocate() support
 - Truncating NFSv4 file opens should also sync O_DIRECT writes
 - Prevent infinite loop in rpcrdma_ep_create()
 
 Features:
 - Various improvements to the RDMA transport code's handling of memory
   registration
 - Various code cleanups
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Merge tag 'nfs-for-4.1-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs

Pull NFS client updates from Trond Myklebust:
 "Another set of mainly bugfixes and a couple of cleanups.  No new
  functionality in this round.

  Highlights include:

  Stable patches:
   - Fix a regression in /proc/self/mountstats
   - Fix the pNFS flexfiles O_DIRECT support
   - Fix high load average due to callback thread sleeping

  Bugfixes:
   - Various patches to fix the pNFS layoutcommit support
   - Do not cache pNFS deviceids unless server notifications are enabled
   - Fix a SUNRPC transport reconnection regression
   - make debugfs file creation failure non-fatal in SUNRPC
   - Another fix for circular directory warnings on NFSv4 "junctioned"
     mountpoints
   - Fix locking around NFSv4.2 fallocate() support
   - Truncating NFSv4 file opens should also sync O_DIRECT writes
   - Prevent infinite loop in rpcrdma_ep_create()

  Features:
   - Various improvements to the RDMA transport code's handling of
     memory registration
   - Various code cleanups"

* tag 'nfs-for-4.1-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs: (55 commits)
  fs/nfs: fix new compiler warning about boolean in switch
  nfs: Remove unneeded casts in nfs
  NFS: Don't attempt to decode missing directory entries
  Revert "nfs: replace nfs_add_stats with nfs_inc_stats when add one"
  NFS: Rename idmap.c to nfs4idmap.c
  NFS: Move nfs_idmap.h into fs/nfs/
  NFS: Remove CONFIG_NFS_V4 checks from nfs_idmap.h
  NFS: Add a stub for GETDEVICELIST
  nfs: remove WARN_ON_ONCE from nfs_direct_good_bytes
  nfs: fix DIO good bytes calculation
  nfs: Fetch MOUNTED_ON_FILEID when updating an inode
  sunrpc: make debugfs file creation failure non-fatal
  nfs: fix high load average due to callback thread sleeping
  NFS: Reduce time spent holding the i_mutex during fallocate()
  NFS: Don't zap caches on fallocate()
  xprtrdma: Make rpcrdma_{un}map_one() into inline functions
  xprtrdma: Handle non-SEND completions via a callout
  xprtrdma: Add "open" memreg op
  xprtrdma: Add "destroy MRs" memreg op
  xprtrdma: Add "reset MRs" memreg op
  ...
2015-04-26 17:33:59 -07:00
Benjamin Coddington ce85cfbed6 NFS: Don't attempt to decode missing directory entries
If a READDIR reply comes back without any page data, avoid a NULL pointer
dereference in xdr_copy_to_scratch().

BUG: unable to handle kernel NULL pointer dereference at 0000000000000001
IP: [<ffffffff813a378d>] memcpy+0xd/0x110
...
Call Trace:
	? xdr_inline_decode+0x7a/0xb0 [sunrpc]
	nfs3_decode_dirent+0x73/0x320 [nfsv3]
	nfs_readdir_page_filler+0xd5/0x4e0 [nfs]
	? nfs3_rpc_wrapper.constprop.9+0x42/0xc0 [nfsv3]
	nfs_readdir_xdr_to_array+0x1fa/0x330 [nfs]
	? mem_cgroup_commit_charge+0xac/0x160
	? nfs_readdir_xdr_to_array+0x330/0x330 [nfs]
	nfs_readdir_filler+0x22/0x90 [nfs]
	do_read_cache_page+0x7e/0x1a0
	read_cache_page+0x1c/0x20
	nfs_readdir+0x18e/0x660 [nfs]
	? nfs3_xdr_dec_getattr3res+0x80/0x80 [nfsv3]
	iterate_dir+0x97/0x130
	SyS_getdents+0x94/0x120
	? fillonedir+0xd0/0xd0
	system_call_fastpath+0x12/0x17

Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-04-23 15:16:15 -04:00
David Howells 2b0143b5c9 VFS: normal filesystems (and lustre): d_inode() annotations
that's the bulk of filesystem drivers dealing with inodes of their own

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-04-15 15:06:57 -04:00
Trond Myklebust fa9233699c NFS: Don't require a filehandle to refresh the inode in nfs_prime_dcache()
If the server does not return a valid set of attributes that we can
use to either create a file or refresh the inode, then there is no
value in calling nfs_prime_dcache().

However if we're just refreshing the inode using the attributes that
the server returned, then it shouldn't matter whether or not we have
a filehandle, as long as we check the fsid+fileid combination.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-03-01 23:23:07 -05:00
Trond Myklebust 6c441c254e NFS: Don't invalidate a submounted dentry in nfs_prime_dcache()
If we're traversing a directory which contains a submounted filesystem,
or one that has a referral, the NFS server that is processing the READDIR
request will often return information for the underlying (mounted-on)
directory. It may, or may not, also return filehandle information.

If this happens, and the lookup in nfs_prime_dcache() returns the
dentry for the submounted directory, the filehandle comparison will
fail, and we call d_invalidate(). Post-commit 8ed936b567
("vfs: Lazily remove mounts on unlinked files and directories."), this
means the entire subtree is unmounted.

The following minimal patch addresses this problem by punting on
the invalidation if there is a submount.

Kudos to Neil Brown <neilb@suse.de> for having tracked down this
issue (see link).

Reported-by: Nix <nix@esperi.org.uk>
Link: http://lkml.kernel.org/r/87iofju9ht.fsf@spindle.srvr.nix
Cc: stable@vger.kernel.org # 3.18+
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2015-03-01 23:23:06 -05:00
Al Viro ba00410b81 Merge branch 'iov_iter' into for-next 2014-12-08 20:39:29 -05:00
Al Viro a455589f18 assorted conversions to %p[dD]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-11-19 13:01:20 -05:00
Al Viro 41d28bca2d switch d_materialise_unique() users to d_splice_alias()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-11-19 13:01:20 -05:00
Trond Myklebust 809fd143de NFSv4: Ensure nfs_atomic_open set the dentry verifier on ENOENT
If the OPEN rpc call to the server fails with an ENOENT call, nfs_atomic_open
will create a negative dentry for that file, however it currently fails
to call nfs_set_verifier(), thus causing the dentry to be immediately
revalidated on the next call to nfs_lookup_revalidate() instead of following
the usual lookup caching rules.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2014-11-04 19:53:49 -06:00
Eric W. Biederman 5542aa2fa7 vfs: Make d_invalidate return void
Now that d_invalidate can no longer fail, stop returning a useless
return code.  For the few callers that checked the return code update
remove the handling of d_invalidate failure.

Reviewed-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-10-09 02:38:57 -04:00
Eric W. Biederman 9b053f3207 vfs: Remove unnecessary calls of check_submounts_and_drop
Now that check_submounts_and_drop can not fail and is called from
d_invalidate there is no longer a need to call check_submounts_and_drom
from filesystem d_revalidate methods so remove it.

Reviewed-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-10-09 02:38:56 -04:00
NeilBrown 50d77739fa NFS: fix two problems in lookup_revalidate in RCU-walk
1/ rcu_dereference isn't correct: that field isn't
   RCU protected.   It could potentially change at any time
   so ACCESS_ONCE might be justified.

   changes to ->d_parent are protected by ->d_seq.  However
   that isn't always checked after ->d_revalidate is called,
   so it is safest to keep the double-check that ->d_parent
   hasn't changed at the end of these functions.

2/ in nfs4_lookup_revalidate, "->d_parent" was forgotten.
   So 'parent' was not the parent of 'dentry'.
   This fails safe is the context is that dentry->d_inode is
   NULL, and the result of parent->d_inode being NULL is
   that ECHILD is returned, which is always safe.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2014-08-04 09:22:08 -04:00
NeilBrown f682a398b2 NFS: allow lockless access to access_cache
The access cache is used during RCU-walk path lookups, so it is best
to avoid locking if possible as taking a lock kills concurrency.

The rbtree is not rcu-safe and cannot easily be made so.
Instead we simply check the last (i.e. most recent) entry on the LRU
list.  If this doesn't match, then we return -ECHILD and retry in
lock/refcount mode.

This requires freeing the nfs_access_entry struct with rcu, and
requires using rcu access primatives when adding entries to the lru, and
when examining the last entry.

Calling put_rpccred before kfree_rcu looks a bit odd, but as
put_rpccred already provides rcu protection, we know that the cred will
not actually be freed until the next grace period, so any concurrent
access will be safe.

This patch provides about 5% performance improvement on a stat-heavy
synthetic work load with 4 threads on a 2-core CPU.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2014-08-03 17:14:13 -04:00
NeilBrown 1fa1e38447 NFS: teach nfs_lookup_verify_inode to handle LOOKUP_RCU
It fails with -ECHILD rather than make an RPC call.

This allows nfs_lookup_revalidate to call it in RCU-walk mode.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2014-08-03 17:14:13 -04:00
NeilBrown 912a108da7 NFS: teach nfs_neg_need_reval to understand LOOKUP_RCU
This requires nfs_check_verifier to take an rcu_walk flag, and requires
an rcu version of nfs_revalidate_inode which returns -ECHILD rather
than making an RPC call.

With this, nfs_lookup_revalidate can call nfs_neg_need_reval in
RCU-walk mode.

We can also move the LOOKUP_RCU check past the nfs_check_verifier()
call in nfs_lookup_revalidate.

If RCU_WALK prevents nfs_check_verifier or nfs_neg_need_reval from
doing a full check, they return a status indicating that a revalidation
is required.  As this revalidation will not be possible in RCU_WALK
mode, -ECHILD will ultimately be returned, which is the desired result.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2014-08-03 17:14:12 -04:00
NeilBrown f3324a2a94 NFS: support RCU_WALK in nfs_permission()
nfs_permission makes two calls which are not always safe in RCU_WALK,
rpc_lookup_cred and nfs_do_access.

The second can easily be made rcu-safe by aborting with -ECHILD before
making the RPC call.

The former can be made rcu-safe by calling rpc_lookup_cred_nonblock()
instead.
As this will almost always succeed, we use it even when RCU_WALK
isn't being used as it still saves some spinlocks in a common case.
We only fall back to rpc_lookup_cred() if rpc_lookup_cred_nonblock()
fails and MAY_NOT_BLOCK isn't set.

This optimisation (always trying rpc_lookup_cred_nonblock()) is
particularly important when a security module is active.
In that case inode_permission() may return -ECHILD from
security_inode_permission() even though ->permission() succeeded in
RCU_WALK mode.
This leads to may_lookup() retrying inode_permission after performing
unlazy_walk().  The spinlock that rpc_lookup_cred() takes is often
more expensive than anything security_inode_permission() does, so that
spinlock becomes the main bottleneck.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2014-08-03 17:14:12 -04:00
NeilBrown d51ac1a8e9 NFS: prepare for RCU-walk support but pushing tests later in code.
nfs_lookup_revalidate, nfs4_lookup_revalidate, and nfs_permission
all need to understand and handle RCU-walk for NFS to gain the
benefits of RCU-walk for cached information.

Currently these functions all immediately return -ECHILD
if the relevant flag (LOOKUP_RCU or MAY_NOT_BLOCK) is set.

This patch pushes those tests later in the code so that we only abort
immediately before we enter rcu-unsafe code.  As subsequent patches
make that rcu-unsafe code rcu-safe, several of these new tests will
disappear.

With this patch there are several paths through the code which will no
longer return -ECHILD during an RCU-walk.  However these are mostly
error paths or other uninteresting cases.

A noteworthy change in nfs_lookup_revalidate is that we don't take
(or put) the reference to ->d_parent when LOOKUP_RCU is set.
Rather we rcu_dereference ->d_parent, and check that ->d_inode
is not NULL.  We also check that ->d_parent hasn't changed after
all the tests.

In nfs4_lookup_revalidate we simply avoid testing LOOKUP_RCU on the
path that only calls nfs_lookup_revalidate() as that function
already performs the required test.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2014-08-03 17:14:11 -04:00
NeilBrown 49317a7fda NFS: nfs4_lookup_revalidate: only evaluate parent if it will be used.
nfs4_lookup_revalidate only uses 'parent' to get 'dir', and only
uses 'dir' if 'inode == NULL'.

So we don't need to find out what 'parent' or 'dir' is until we
know that 'inode' is NULL.

By moving 'dget_parent' inside the 'if', we can reduce the number of
call sites for 'dput(parent)'.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2014-08-03 17:14:11 -04:00
Trond Myklebust 3a505845cd NFS: Enforce an upper limit on the number of cached access call
This may be used to limit the number of cached credentials building up
inside the access cache.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2014-08-03 17:03:22 -04:00
Peter Zijlstra 4e857c58ef arch: Mass conversion of smp_mb__*()
Mostly scripted conversion of the smp_mb__* barriers.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/n/tip-55dhyhocezdw1dg7u19hmh1u@git.kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-arch@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-04-18 14:20:48 +02:00
Linus Torvalds 2b3a8fd735 NFS client updates for Linux 3.15
Highlights include:
 
 - Stable fix for a use after free issue in the NFSv4.1 open code
 - Fix the SUNRPC bi-directional RPC code to account for TCP segmentation
 - Optimise usage of readdirplus when confronted with 'ls -l' situations
 - Soft mount bugfixes
 - NFS over RDMA bugfixes
 - NFSv4 close locking fixes
 - Various NFSv4.x client state management optimisations
 - Rename/unlink code cleanups
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Merge tag 'nfs-for-3.15-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs

Pull NFS client updates from Trond Myklebust:
 "Highlights include:

   - Stable fix for a use after free issue in the NFSv4.1 open code
   - Fix the SUNRPC bi-directional RPC code to account for TCP segmentation
   - Optimise usage of readdirplus when confronted with 'ls -l' situations
   - Soft mount bugfixes
   - NFS over RDMA bugfixes
   - NFSv4 close locking fixes
   - Various NFSv4.x client state management optimisations
   - Rename/unlink code cleanups"

* tag 'nfs-for-3.15-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs: (28 commits)
  nfs: pass string length to pr_notice message about readdir loops
  NFSv4: Fix a use-after-free problem in open()
  SUNRPC: rpc_restart_call/rpc_restart_call_prepare should clear task->tk_status
  SUNRPC: Don't let rpc_delay() clobber non-timeout errors
  SUNRPC: Ensure call_connect_status() deals correctly with SOFTCONN tasks
  SUNRPC: Ensure call_status() deals correctly with SOFTCONN tasks
  NFSv4: Ensure we respect soft mount timeouts during trunking discovery
  NFSv4: Schedule recovery if nfs40_walk_client_list() is interrupted
  NFS: advertise only supported callback netids
  SUNRPC: remove KERN_INFO from dprintk() call sites
  SUNRPC: Fix large reads on NFS/RDMA
  NFS: Clean up: revert increase in READDIR RPC buffer max size
  SUNRPC: Ensure that call_bind times out correctly
  SUNRPC: Ensure that call_connect times out correctly
  nfs: emit a fsnotify_nameremove call in sillyrename codepath
  nfs: remove synchronous rename code
  nfs: convert nfs_rename to use async_rename infrastructure
  nfs: make nfs_async_rename non-static
  nfs: abstract out code needed to complete a sillyrename
  NFSv4: Clear the open state flags if the new stateid does not match
  ...
2014-04-06 10:09:38 -07:00
Jeff Layton 9581a4ae75 nfs: pass string length to pr_notice message about readdir loops
There is no guarantee that the strings in the nfs_cache_array will be
NULL-terminated. In the event that we end up hitting a readdir loop, we
need to ensure that we pass the warning message the length of the
string.

Reported-by: Lachlan McIlroy <lmcilroy@redhat.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2014-04-05 09:25:42 -04:00
Jeff Layton 80a491fd40 nfs: convert nfs_rename to use async_rename infrastructure
There isn't much sense in maintaining two separate versions of rename
code. Convert nfs_rename to use the asynchronous rename infrastructure
that nfs_sillyrename uses, and emulate synchronous behavior by having
the task just wait on the reply.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Tested-by: Anna Schumaker <Anna.Schumaker@netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2014-03-17 15:14:17 -04:00
Trond Myklebust 311324ad17 NFS: Be more aggressive in using readdirplus for 'ls -l' situations
Try to detect 'ls -l' by having nfs_getattr() look at whether or not
there is an opendir() file descriptor for the parent directory.
If so, then assume that we want to force use of readdirplus in order
to avoid the multiple GETATTR calls over the wire.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2014-02-11 14:01:20 -05:00
Rafael Aquini a0b54adda3 mm: fix page leak at nfs_symlink()
Changes in commit a0b8cab3b9 ("mm: remove lru parameter from
__pagevec_lru_add and remove parts of pagevec API") have introduced a
call to add_to_page_cache_lru() which causes a leak in nfs_symlink() as
now the page gets an extra refcount that is not dropped.

Jan Stancek observed and reported the leak effect while running test8
from Connectathon Testsuite.  After several iterations over the test
case, which creates several symlinks on a NFS mountpoint, the test
system was quickly getting into an out-of-memory scenario.

This patch fixes the page leak by dropping that extra refcount
add_to_page_cache_lru() is grabbing.

Signed-off-by: Jan Stancek <jstancek@redhat.com>
Signed-off-by: Rafael Aquini <aquini@redhat.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Jeff Layton <jlayton@redhat.com>
Cc: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: <stable@vger.kernel.org>	[3.11.x+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-02-10 16:01:42 -08:00
Jeff Layton 4db72b40fd nfs: add memory barriers around NFS_INO_INVALID_DATA and NFS_INO_INVALIDATING
If the setting of NFS_INO_INVALIDATING gets reordered to before the
clearing of NFS_INO_INVALID_DATA, then another task may hit a race
window where both appear to be clear, even though the inode's pages are
still in need of invalidation. Fix this by adding the appropriate memory
barriers.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2014-01-28 14:48:18 -05:00
Jeff Layton d529ef83c3 NFS: fix the handling of NFS_INO_INVALID_DATA flag in nfs_revalidate_mapping
There is a possible race in how the nfs_invalidate_mapping function is
handled.  Currently, we go and invalidate the pages in the file and then
clear NFS_INO_INVALID_DATA.

The problem is that it's possible for a stale page to creep into the
mapping after the page was invalidated (i.e., via readahead). If another
writer comes along and sets the flag after that happens but before
invalidate_inode_pages2 returns then we could clear the flag
without the cache having been properly invalidated.

So, we must clear the flag first and then invalidate the pages. Doing
this however, opens another race:

It's possible to have two concurrent read() calls that end up in
nfs_revalidate_mapping at the same time. The first one clears the
NFS_INO_INVALID_DATA flag and then goes to call nfs_invalidate_mapping.

Just before calling that though, the other task races in, checks the
flag and finds it cleared. At that point, it trusts that the mapping is
good and gets the lock on the page, allowing the read() to be satisfied
from the cache even though the data is no longer valid.

These effects are easily manifested by running diotest3 from the LTP
test suite on NFS. That program does a series of DIO writes and buffered
reads. The operations are serialized and page-aligned but the existing
code fails the test since it occasionally allows a read to come out of
the cache incorrectly. While mixing direct and buffered I/O isn't
recommended, I believe it's possible to hit this in other ways that just
use buffered I/O, though that situation is much harder to reproduce.

The problem is that the checking/clearing of that flag and the
invalidation of the mapping really need to be atomic. Fix this by
serializing concurrent invalidations with a bitlock.

At the same time, we also need to allow other places that check
NFS_INO_INVALID_DATA to check whether we might be in the middle of
invalidating the file, so fix up a couple of places that do that
to look for the new NFS_INO_INVALIDATING flag.

Doing this requires us to be careful not to set the bitlock
unnecessarily, so this code only does that if it believes it will
be doing an invalidation.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2014-01-27 15:35:56 -05:00
Niels de Vos 1e8968c5b0 NFS: dprintk() should not print negative fileids and inode numbers
A fileid in NFS is a uint64. There are some occurrences where dprintk()
outputs a signed fileid. This leads to confusion and more difficult to
read debugging (negative fileids matching positive inode numbers).

Signed-off-by: Niels de Vos <ndevos@redhat.com>
CC: Santosh Pradhan <spradhan@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2014-01-05 15:51:23 -05:00
Linus Torvalds 9bc9ccd7db Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs updates from Al Viro:
 "All kinds of stuff this time around; some more notable parts:

   - RCU'd vfsmounts handling
   - new primitives for coredump handling
   - files_lock is gone
   - Bruce's delegations handling series
   - exportfs fixes

  plus misc stuff all over the place"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (101 commits)
  ecryptfs: ->f_op is never NULL
  locks: break delegations on any attribute modification
  locks: break delegations on link
  locks: break delegations on rename
  locks: helper functions for delegation breaking
  locks: break delegations on unlink
  namei: minor vfs_unlink cleanup
  locks: implement delegations
  locks: introduce new FL_DELEG lock flag
  vfs: take i_mutex on renamed file
  vfs: rename I_MUTEX_QUOTA now that it's not used for quotas
  vfs: don't use PARENT/CHILD lock classes for non-directories
  vfs: pull ext4's double-i_mutex-locking into common code
  exportfs: fix quadratic behavior in filehandle lookup
  exportfs: better variable name
  exportfs: move most of reconnect_path to helper function
  exportfs: eliminate unused "noprogress" counter
  exportfs: stop retrying once we race with rename/remove
  exportfs: clear DISCONNECTED on all parents sooner
  exportfs: more detailed comment for path_reconnect
  ...
2013-11-13 15:34:18 +09:00
Trond Myklebust c698dbf9fe Merge branch 'fscache' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs into linux-next
Pull fs-cache fixes from David Howells:

Can you pull these commits to fix an issue with NFS whereby caching can be
enabled on a file that is open for writing by subsequently opening it for
reading.  This can be made to crash by opening it for writing again if you're
quick enough.

The gist of the patchset is that the cookie should be acquired at inode
creation only and subsequently enabled and disabled as appropriate (which
dispenses with the backing objects when they're not needed).

The extra synchronisation that NFS does can then be dispensed with as it is
thenceforth managed by FS-Cache.

Could you send these on to Linus?

This likely will need fixing also in CIFS and 9P also once the FS-Cache
changes are upstream.  AFS and Ceph are probably safe.

* 'fscache' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  NFS: Use i_writecount to control whether to get an fscache cookie in nfs_open()
  FS-Cache: Provide the ability to enable/disable cookies
  FS-Cache: Add use/unuse/wake cookie wrappers
2013-10-28 19:36:46 -04:00
J. Bruce Fields a3f432bfd0 nfs: use IS_ROOT not DCACHE_DISCONNECTED
This check was added by Al Viro with
d9e80b7de9 "nfs d_revalidate() is too
trigger-happy with d_drop()", with the explanation that we don't want to
remove the root of a disconnected tree, which will still be included on
the s_anon list.

But DCACHE_DISCONNECTED does *not* actually identify dentries that are
disconnected from the dentry tree or hashed on s_anon.  IS_ROOT() is the
way to do that.

Also add a comment from Al's commit to remind us why this check is
there.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2013-10-28 19:19:19 -04:00
Al Viro 6de1472f1a nfs: use %p[dD] instead of open-coded (and often racy) equivalents
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-10-24 23:34:50 -04:00
David Howells f1fe29b4a0 NFS: Use i_writecount to control whether to get an fscache cookie in nfs_open()
Use i_writecount to control whether to get an fscache cookie in nfs_open() as
NFS does not do write caching yet.  I *think* this is the cause of a problem
encountered by Mark Moseley whereby __fscache_uncache_page() gets a NULL
pointer dereference because cookie->def is NULL:

BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
IP: [<ffffffff812a1903>] __fscache_uncache_page+0x23/0x160
PGD 0
Thread overran stack, or stack corrupted
Oops: 0000 [#1] SMP
Modules linked in: ...
CPU: 7 PID: 18993 Comm: php Not tainted 3.11.1 #1
Hardware name: Dell Inc. PowerEdge R420/072XWF, BIOS 1.3.5 08/21/2012
task: ffff8804203460c0 ti: ffff880420346640
RIP: 0010:[<ffffffff812a1903>] __fscache_uncache_page+0x23/0x160
RSP: 0018:ffff8801053af878 EFLAGS: 00210286
RAX: 0000000000000000 RBX: ffff8800be2f8780 RCX: ffff88022ffae5e8
RDX: 0000000000004c66 RSI: ffffea00055ff440 RDI: ffff8800be2f8780
RBP: ffff8801053af898 R08: 0000000000000001 R09: 0000000000000003
R10: 0000000000000000 R11: 0000000000000000 R12: ffffea00055ff440
R13: 0000000000001000 R14: ffff8800c50be538 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff88042fc60000(0063) knlGS:00000000e439c700
CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000000000010 CR3: 0000000001d8f000 CR4: 00000000000607f0
Stack:
...
Call Trace:
[<ffffffff81365a72>] __nfs_fscache_invalidate_page+0x42/0x70
[<ffffffff813553d5>] nfs_invalidate_page+0x75/0x90
[<ffffffff811b8f5e>] truncate_inode_page+0x8e/0x90
[<ffffffff811b90ad>] truncate_inode_pages_range.part.12+0x14d/0x620
[<ffffffff81d6387d>] ? __mutex_lock_slowpath+0x1fd/0x2e0
[<ffffffff811b95d3>] truncate_inode_pages_range+0x53/0x70
[<ffffffff811b969d>] truncate_inode_pages+0x2d/0x40
[<ffffffff811b96ff>] truncate_pagecache+0x4f/0x70
[<ffffffff81356840>] nfs_setattr_update_inode+0xa0/0x120
[<ffffffff81368de4>] nfs3_proc_setattr+0xc4/0xe0
[<ffffffff81357f78>] nfs_setattr+0xc8/0x150
[<ffffffff8122d95b>] notify_change+0x1cb/0x390
[<ffffffff8120a55b>] do_truncate+0x7b/0xc0
[<ffffffff8121f96c>] do_last+0xa4c/0xfd0
[<ffffffff8121ffbc>] path_openat+0xcc/0x670
[<ffffffff81220a0e>] do_filp_open+0x4e/0xb0
[<ffffffff8120ba1f>] do_sys_open+0x13f/0x2b0
[<ffffffff8126aaf6>] compat_SyS_open+0x36/0x50
[<ffffffff81d7204c>] sysenter_dispatch+0x7/0x24

The code at the instruction pointer was disassembled:

> (gdb) disas __fscache_uncache_page
> Dump of assembler code for function __fscache_uncache_page:
> ...
> 0xffffffff812a18ff <+31>: mov 0x48(%rbx),%rax
> 0xffffffff812a1903 <+35>: cmpb $0x0,0x10(%rax)
> 0xffffffff812a1907 <+39>: je 0xffffffff812a19cd <__fscache_uncache_page+237>

These instructions make up:

	ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);

That cmpb is the faulting instruction (%rax is 0).  So cookie->def is NULL -
which presumably means that the cookie has already been at least partway
through __fscache_relinquish_cookie().

What I think may be happening is something like a three-way race on the same
file:

	PROCESS 1	PROCESS 2	PROCESS 3
	===============	===============	===============
	open(O_TRUNC|O_WRONLY)
			open(O_RDONLY)
					open(O_WRONLY)
	-->nfs_open()
	-->nfs_fscache_set_inode_cookie()
	nfs_fscache_inode_lock()
	nfs_fscache_disable_inode_cookie()
	__fscache_relinquish_cookie()
	nfs_inode->fscache = NULL
	<--nfs_fscache_set_inode_cookie()

			-->nfs_open()
			-->nfs_fscache_set_inode_cookie()
			nfs_fscache_inode_lock()
			nfs_fscache_enable_inode_cookie()
			__fscache_acquire_cookie()
			nfs_inode->fscache = cookie
			<--nfs_fscache_set_inode_cookie()
	<--nfs_open()
	-->nfs_setattr()
	...
	...
	-->nfs_invalidate_page()
	-->__nfs_fscache_invalidate_page()
	cookie = nfsi->fscache
					-->nfs_open()
					-->nfs_fscache_set_inode_cookie()
					nfs_fscache_inode_lock()
					nfs_fscache_disable_inode_cookie()
					-->__fscache_relinquish_cookie()
	-->__fscache_uncache_page(cookie)
	<crash>
					<--__fscache_relinquish_cookie()
					nfs_inode->fscache = NULL
					<--nfs_fscache_set_inode_cookie()

What is needed is something to prevent process #2 from reacquiring the cookie
- and I think checking i_writecount should do the trick.

It's also possible to have a two-way race on this if the file is opened
O_TRUNC|O_RDONLY instead.

Reported-by: Mark Moseley <moseleymark@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
2013-09-27 18:40:25 +01:00