Commit Graph

484 Commits

Author SHA1 Message Date
Linus Torvalds e419b4cc58 vfs: make word-at-a-time accesses handle a non-existing page
It turns out that there are more cases than CONFIG_DEBUG_PAGEALLOC that
can have holes in the kernel address space: it seems to happen easily
with Xen, and it looks like the AMD gart64 code will also punch holes
dynamically.

Actually hitting that case is still very unlikely, so just do the
access, and take an exception and fix it up for the very unlikely case
of it being a page-crosser with no next page.

And hey, this abstraction might even help other architectures that have
other issues with unaligned word accesses than the possible missing next
page.  IOW, this could do the byte order magic too.

Peter Anvin fixed a thinko in the shifting for the exception case.

Reported-and-tested-by: Jana Saout <jana@saout.de>
Cc:  Peter Anvin <hpa@zytor.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-03 14:01:40 -07:00
Linus Torvalds f68e556e23 Make the "word-at-a-time" helper functions more commonly usable
I have a new optimized x86 "strncpy_from_user()" that will use these
same helper functions for all the same reasons the name lookup code uses
them.  This is preparation for that.

This moves them into an architecture-specific header file.  It's
architecture-specific for two reasons:

 - some of the functions are likely to want architecture-specific
   implementations.  Even if the current code happens to be "generic" in
   the sense that it should work on any little-endian machine, it's
   likely that the "multiply by a big constant and shift" implementation
   is less than optimal for an architecture that has a guaranteed fast
   bit count instruction, for example.

 - I expect that if architectures like sparc want to start playing
   around with this, we'll need to abstract out a few more details (in
   particular the actual unaligned accesses).  So we're likely to have
   more architecture-specific stuff if non-x86 architectures start using
   this.

   (and if it turns out that non-x86 architectures don't start using
   this, then having it in an architecture-specific header is still the
   right thing to do, of course)

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-04-06 13:54:56 -07:00
J. Bruce Fields c0d0259481 vfs: fix out-of-date dentry_unhash() comment
64252c75a2 "vfs: remove dget() from
dentry_unhash()" changed the implementation but not the comment.

Cc: Sage Weil <sage@newdream.net>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-03-31 16:03:17 -04:00
Miklos Szeredi bad6118978 vfs: split __lookup_hash
Split __lookup_hash into two component functions:

 lookup_dcache - tries cached lookup, returns whether real lookup is needed
 lookup_real - calls i_op->lookup

This eliminates code duplication between d_alloc_and_lookup() and
d_inode_lookup().

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-03-31 16:03:17 -04:00
Al Viro 81e6f52089 untangling do_lookup() - take __lookup_hash()-calling case out of line.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-03-31 16:03:17 -04:00
Al Viro a32555466c untangling do_lookup() - switch to calling __lookup_hash()
now we have __lookup_hash() open-coded if !dentry case;
just call the damn thing instead...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-03-31 16:03:16 -04:00
Al Viro a6ecdfcfba untangling do_lookup() - merge d_alloc_and_lookup() callers
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-03-31 16:03:16 -04:00
Al Viro ec335e91a4 untangling do_lookup() - merge failure exits in !dentry case
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-03-31 16:03:16 -04:00
Al Viro d774a058d9 untangling do_lookup() - massage !dentry case towards __lookup_hash()
Reorder if-else cases for starters...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-03-31 16:03:16 -04:00
Al Viro 08b0ab7c20 untangling do_lookup() - get rid of need_reval in !dentry case
Everything arriving into if (!dentry) will have need_reval = 1.
Indeed, the only way to get there with need_reval reset to 0 would
be via
	if (unlikely(d_need_lookup(dentry)))
		goto unlazy;
	if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) {
		status = d_revalidate(dentry, nd);
	if (unlikely(status <= 0)) {
		if (status != -ECHILD)
			need_reval = 0;
		goto unlazy;
...
unlazy:
	/* no assignments to dentry */
	if (dentry && unlikely(d_need_lookup(dentry))) {
		dput(dentry);
		dentry = NULL;
	}
and if d_need_lookup() had already been false the first time around, it
will remain false on the second call as well.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-03-31 16:03:16 -04:00
Al Viro acc9cb3cd4 untangling do_lookup() - eliminate a loop.
d_lookup() *will* fail after successful d_invalidate(), if we are
holding i_mutex all along.  IOW, we don't need to jump back to
l: - we know what path will be taken there and can do that (i.e.
d_alloc_and_lookup()) directly.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-03-31 16:03:16 -04:00
Al Viro 37c17e1f37 untangling do_lookup() - expand the area under ->i_mutex
keep holding ->i_mutex over revalidation parts

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-03-31 16:03:16 -04:00
Al Viro 3f6c7c71a2 untangling do_lookup() - isolate !dentry stuff from the rest of it.
Duplicate the revalidation-related parts into if (!dentry) branch.
Next step will be to pull them under i_mutex.

This and the next 8 commits are more or less a splitup of patch
by Miklos; folks, when you are working with something that convoluted,
carve your patches up into easily reviewed steps, especially when
a lot of codepaths involved are rarely hit...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-03-31 16:03:16 -04:00
Miklos Szeredi cda309de25 vfs: move MAY_EXEC check from __lookup_hash()
The only caller of __lookup_hash() that needs the exec permission check on
parent is lookup_one_len().

All lookup_hash() callers already checked permission in LOOKUP_PARENT walk.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-03-31 16:03:16 -04:00
Miklos Szeredi 3637c05d88 vfs: don't revalidate just looked up dentry
__lookup_hash() calls ->lookup() if the dentry needs lookup and on success
revalidates the dentry (all under dir->i_mutex).

While this is harmless it doesn't make a lot of sense.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-03-31 16:03:16 -04:00
Miklos Szeredi fa4ee15951 vfs: fix d_need_lookup/d_revalidate order in do_lookup
Doing revalidate on a dentry which has not yet been looked up makes no sense.

Move the d_need_lookup() check before d_revalidate().

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-03-31 16:03:16 -04:00
Linus Torvalds 11bcb32848 The following text was taken from the original review request:
"[PATCH 0/3] RFC - module.h usage cleanups in fs/ and lib/"
 		https://lkml.org/lkml/2012/2/29/589
 --
 
 Fix up files in fs/ and lib/ dirs to only use module.h if they really
 need it.
 
 These are trivial in scope vs. the work done previously.  We now have
 things where any few remaining cleanups can be farmed out to arch or
 subsystem maintainers, and I have done so when possible.  What is
 remaining here represents the bits that don't clearly lie within a
 single arch/subsystem boundary, like the fs dir and the lib dir.
 
 Some duplicate includes arising from overlapping fixes from
 independent subsystem maintainer submissions are also quashed.
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Merge tag 'module-for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux

Pull cleanup of fs/ and lib/ users of module.h from Paul Gortmaker:
 "Fix up files in fs/ and lib/ dirs to only use module.h if they really
  need it.

  These are trivial in scope vs the work done previously.  We now have
  things where any few remaining cleanups can be farmed out to arch or
  subsystem maintainers, and I have done so when possible.  What is
  remaining here represents the bits that don't clearly lie within a
  single arch/subsystem boundary, like the fs dir and the lib dir.

  Some duplicate includes arising from overlapping fixes from
  independent subsystem maintainer submissions are also quashed."

Fix up trivial conflicts due to clashes with other include file cleanups
(including some due to the previous bug.h cleanup pull).

* tag 'module-for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux:
  lib: reduce the use of module.h wherever possible
  fs: reduce the use of module.h wherever possible
  includecheck: delete any duplicate instances of module.h
2012-03-24 10:24:31 -07:00
Linus Torvalds f7493e5d9c vfs: tidy up sparse warnings in fs/namei.c
While doing the fs/namei.c cleanups, I ran sparse on it, and it pointed
out other large integers and a couple of cases of us using '0' instead
of the proper 'NULL'.

Sparse still doesn't understand some of the conditional locking going
on, but that's no excuse for not fixing up the trivial stuff.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 16:10:40 -07:00
Linus Torvalds 989412bbd2 vfs: tidy up fs/namei.c byte-repeat word constants
In commit commit 1de5b41cd3 ("fs/namei.c: fix warnings on 32-bit")
Andrew said that there must be a tidier way of doing this.

This is that tidier way.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 15:58:27 -07:00
Al Viro f132c5be05 Fix full_name_hash() behaviour when length is a multiple of 8
We want it to match what hash_name() is doing, which means extra
multiply by 9 in this case...

Reported-and-Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-22 15:10:43 -07:00
Linus Torvalds 95211279c5 Merge branch 'akpm' (Andrew's patch-bomb)
Merge first batch of patches from Andrew Morton:
 "A few misc things and all the MM queue"

* emailed from Andrew Morton <akpm@linux-foundation.org>: (92 commits)
  memcg: avoid THP split in task migration
  thp: add HPAGE_PMD_* definitions for !CONFIG_TRANSPARENT_HUGEPAGE
  memcg: clean up existing move charge code
  mm/memcontrol.c: remove unnecessary 'break' in mem_cgroup_read()
  mm/memcontrol.c: remove redundant BUG_ON() in mem_cgroup_usage_unregister_event()
  mm/memcontrol.c: s/stealed/stolen/
  memcg: fix performance of mem_cgroup_begin_update_page_stat()
  memcg: remove PCG_FILE_MAPPED
  memcg: use new logic for page stat accounting
  memcg: remove PCG_MOVE_LOCK flag from page_cgroup
  memcg: simplify move_account() check
  memcg: remove EXPORT_SYMBOL(mem_cgroup_update_page_stat)
  memcg: kill dead prev_priority stubs
  memcg: remove PCG_CACHE page_cgroup flag
  memcg: let css_get_next() rely upon rcu_read_lock()
  cgroup: revert ss_id_lock to spinlock
  idr: make idr_get_next() good for rcu_read_lock()
  memcg: remove unnecessary thp check in page stat accounting
  memcg: remove redundant returns
  memcg: enum lru_list lru
  ...
2012-03-22 09:04:48 -07:00
Andrew Morton 1de5b41cd3 fs/namei.c: fix warnings on 32-bit
i386 allnoconfig:

  fs/namei.c: In function 'has_zero':
  fs/namei.c:1617: warning: integer constant is too large for 'unsigned long' type
  fs/namei.c:1617: warning: integer constant is too large for 'unsigned long' type
  fs/namei.c: In function 'hash_name':
  fs/namei.c:1635: warning: integer constant is too large for 'unsigned long' type

There must be a tidier way of doing this.

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-21 17:54:54 -07:00
Linus Torvalds e2a0883e40 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs pile 1 from Al Viro:
 "This is _not_ all; in particular, Miklos' and Jan's stuff is not there
  yet."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (64 commits)
  ext4: initialization of ext4_li_mtx needs to be done earlier
  debugfs-related mode_t whack-a-mole
  hfsplus: add an ioctl to bless files
  hfsplus: change finder_info to u32
  hfsplus: initialise userflags
  qnx4: new helper - try_extent()
  qnx4: get rid of qnx4_bread/qnx4_getblk
  take removal of PF_FORKNOEXEC to flush_old_exec()
  trim includes in inode.c
  um: uml_dup_mmap() relies on ->mmap_sem being held, but activate_mm() doesn't hold it
  um: embed ->stub_pages[] into mmu_context
  gadgetfs: list_for_each_safe() misuse
  ocfs2: fix leaks on failure exits in module_init
  ecryptfs: make register_filesystem() the last potential failure exit
  ntfs: forgets to unregister sysctls on register_filesystem() failure
  logfs: missing cleanup on register_filesystem() failure
  jfs: mising cleanup on register_filesystem() failure
  make configfs_pin_fs() return root dentry on success
  configfs: configfs_create_dir() has parent dentry in dentry->d_parent
  configfs: sanitize configfs_create()
  ...
2012-03-21 13:36:41 -07:00
Linus Torvalds 9f3938346a Merge branch 'kmap_atomic' of git://github.com/congwang/linux
Pull kmap_atomic cleanup from Cong Wang.

It's been in -next for a long time, and it gets rid of the (no longer
used) second argument to k[un]map_atomic().

Fix up a few trivial conflicts in various drivers, and do an "evil
merge" to catch some new uses that have come in since Cong's tree.

* 'kmap_atomic' of git://github.com/congwang/linux: (59 commits)
  feature-removal-schedule.txt: schedule the deprecated form of kmap_atomic() for removal
  highmem: kill all __kmap_atomic() [swarren@nvidia.com: highmem: Fix ARM build break due to __kmap_atomic rename]
  drbd: remove the second argument of k[un]map_atomic()
  zcache: remove the second argument of k[un]map_atomic()
  gma500: remove the second argument of k[un]map_atomic()
  dm: remove the second argument of k[un]map_atomic()
  tomoyo: remove the second argument of k[un]map_atomic()
  sunrpc: remove the second argument of k[un]map_atomic()
  rds: remove the second argument of k[un]map_atomic()
  net: remove the second argument of k[un]map_atomic()
  mm: remove the second argument of k[un]map_atomic()
  lib: remove the second argument of k[un]map_atomic()
  power: remove the second argument of k[un]map_atomic()
  kdb: remove the second argument of k[un]map_atomic()
  udf: remove the second argument of k[un]map_atomic()
  ubifs: remove the second argument of k[un]map_atomic()
  squashfs: remove the second argument of k[un]map_atomic()
  reiserfs: remove the second argument of k[un]map_atomic()
  ocfs2: remove the second argument of k[un]map_atomic()
  ntfs: remove the second argument of k[un]map_atomic()
  ...
2012-03-21 09:40:26 -07:00
Al Viro 68ac1234fb switch touch_atime to struct path
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-03-20 21:29:41 -04:00
Al Viro 8de5277879 vfs: check i_nlink limits in vfs_{mkdir,rename_dir,link}
New field of struct super_block - ->s_max_links.  Maximal allowed
value of ->i_nlink or 0; in the latter case all checks still need
to be done in ->link/->mkdir/->rename instances.  Note that this
limit applies both to directoris and to non-directories.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-03-20 21:29:32 -04:00
Cong Wang e8e3c3d66f fs: remove the second argument of k[un]map_atomic()
Acked-by: Benjamin LaHaise <bcrl@kvack.org>
Signed-off-by: Cong Wang <amwang@redhat.com>
2012-03-20 21:48:21 +08:00
Linus Torvalds b0e37d7ac6 Merge branch 'dcache-word-accesses'
* branch 'dcache-word-accesses':
  vfs: use 'unsigned long' accesses for dcache name comparison and hashing

This does the name hashing and lookup using word-sized accesses when
that is efficient, namely on x86 (although any little-endian machine
with good unaligned accesses would do).

It does very much depend on little-endian logic, but it's a very hot
couple of functions under some real loads, and this patch improves the
performance of __d_lookup_rcu() and link_path_walk() by up to about 30%.
Giving a 10% improvement on some very pathname-heavy benchmarks.

Because we do make unaligned accesses past the filename, the
optimization is disabled when CONFIG_DEBUG_PAGEALLOC is active, and we
effectively depend on the fact that on x86 we don't really ever have the
last page of usable RAM followed immediately by any IO memory (due to
ACPI tables, BIOS buffer areas etc).

Some of the bit operations we do are a bit "subtle".  It's commented,
but you do need to really think about the code.  Or just consider it
black magic.

Thanks to people on G+ for some of the optimized bit tricks.
2012-03-19 16:37:28 -07:00
Miklos Szeredi 7f6c7e62fc vfs: fix return value from do_last()
complete_walk() returns either ECHILD or ESTALE.  do_last() turns this into
ECHILD unconditionally.  If not in RCU mode, this error will reach userspace
which is complete nonsense.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
CC: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-03-10 17:05:30 -05:00
Miklos Szeredi 097b180ca0 vfs: fix double put after complete_walk()
complete_walk() already puts nd->path, no need to do it again at cleanup time.

This would result in Oopses if triggered, apparently the codepath is not too
well exercised.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
CC: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-03-10 17:05:30 -05:00
Linus Torvalds bfcfaa77bd vfs: use 'unsigned long' accesses for dcache name comparison and hashing
Ok, this is hacky, and only works on little-endian machines with goo
unaligned handling.  And even then only with CONFIG_DEBUG_PAGEALLOC
disabled, since it can access up to 7 bytes after the pathname.

But it runs like a bat out of hell.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-08 18:08:44 -08:00
Linus Torvalds ae942ae719 vfs: export full_name_hash() function to modules
Commit 5707c87f "vfs: uninline full_name_hash()" broke the modular
build, because it needs exporting now that it isn't inlined any more.

Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-02 19:40:57 -08:00
Linus Torvalds 200e9ef7ab vfs: split up name hashing in link_path_walk() into helper function
The code in link_path_walk() that finds out the length and the hash of
the next path component is some of the hottest code in the kernel.  And
I have a version of it that does things at the full width of the CPU
wordsize at a time, but that means that we *really* want to split it up
into a separate helper function.

So this re-organizes the code a bit and splits the hashing part into a
helper function called "hash_name()".  It returns the length of the
pathname component, while at the same time computing and writing the
hash to the appropriate location.

The code generation is slightly changed by this patch, but generally for
the better - and the added abstraction actually makes the code easier to
read too.  And the new interface is well suited for replacing just the
"hash_name()" function with alternative implementations.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-02 14:49:24 -08:00
Linus Torvalds 0145acc202 vfs: uninline full_name_hash()
.. and also use it in lookup_one_len() rather than open-coding it.

There aren't any performance-critical users, so inlining it is silly.
But it wouldn't matter if it wasn't for the fact that the word-at-a-time
dentry name patches want to conditionally replace the function, and
uninlining it sets the stage for that.

So again, this is a preparatory patch that doesn't change any semantics,
and only prepares for a much cleaner and testable word-at-a-time dentry
name accessor patch.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-02 14:32:59 -08:00
Paul Gortmaker 630d9c4727 fs: reduce the use of module.h wherever possible
For files only using THIS_MODULE and/or EXPORT_SYMBOL, map
them onto including export.h -- or if the file isn't even
using those, then just delete the include.  Fix up any implicit
include dependencies that were being masked by module.h along
the way.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2012-02-28 19:31:58 -05:00
Miklos Szeredi e188dc02d3 vfs: fix d_inode_lookup() dentry ref leak
d_inode_lookup() leaks a dentry reference on IS_DEADDIR().

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
CC: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-02-13 20:45:37 -05:00
Eric Paris 4043cde8ec audit: do not call audit_getname on error
Just a code cleanup really.  We don't need to make a function call just for
it to return on error.  This also makes the VFS function even easier to follow
and removes a conditional on a hot path.

Signed-off-by: Eric Paris <eparis@redhat.com>
2012-01-17 16:17:01 -05:00
Al Viro ece2ccb668 Merge branches 'vfsmount-guts', 'umode_t' and 'partitions' into Z 2012-01-06 23:15:54 -05:00
Al Viro a73324da7a vfs: move mnt_mountpoint to struct mount
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:57:05 -05:00
Al Viro 0714a53380 vfs: now it can be done - make mnt_parent point to struct mount
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:57:05 -05:00
Al Viro 3376f34fff vfs: mnt_parent moved to struct mount
the second victim...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:57:04 -05:00
Al Viro c71053659e vfs: spread struct mount - __lookup_mnt() result
switch __lookup_mnt() to returning struct mount *; callers adjusted.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:56:58 -05:00
Al Viro a218d0fdc5 switch open and mkdir syscalls to umode_t
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:55:19 -05:00
Al Viro f69aac0006 switch may_mknod() to umode_t
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:55:14 -05:00
Al Viro 1a67aafb5f switch ->mknod() to umode_t
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:54:54 -05:00
Al Viro 4acdaf27eb switch ->create() to umode_t
vfs_create() ignores everything outside of 16bit subset of its
mode argument; switching it to umode_t is obviously equivalent
and it's the only caller of the method

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:54:53 -05:00
Al Viro 18bb1db3e7 switch vfs_mkdir() and ->mkdir() to umode_t
vfs_mkdir() gets int, but immediately drops everything that might not
fit into umode_t and that's the only caller of ->mkdir()...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:54:53 -05:00
Al Viro 8208a22bb8 switch sys_mknodat(2) to umode_t
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:54:52 -05:00
Al Viro a3fbbde70a VFS: we need to set LOOKUP_JUMPED on mountpoint crossing
Mountpoint crossing is similar to following procfs symlinks - we do
not get ->d_revalidate() called for dentry we have arrived at, with
unpleasant consequences for NFS4.

Simple way to reproduce the problem in mainline:

    cat >/tmp/a.c <<'EOF'
    #include <unistd.h>
    #include <fcntl.h>
    #include <stdio.h>
    main()
    {
            struct flock fl = {.l_type = F_RDLCK, .l_whence = SEEK_SET, .l_len = 1};
            if (fcntl(0, F_SETLK, &fl))
                    perror("setlk");
    }
    EOF
    cc /tmp/a.c -o /tmp/test

then on nfs4:

    mount --bind file1 file2
    /tmp/test < file1		# ok
    /tmp/test < file2		# spews "setlk: No locks available"...

What happens is the missing call of ->d_revalidate() after mountpoint
crossing and that's where NFS4 would issue OPEN request to server.

The fix is simple - treat mountpoint crossing the same way we deal with
following procfs-style symlinks.  I.e.  set LOOKUP_JUMPED...

Cc: stable@kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-11-07 14:58:06 -08:00
Andy Whitcroft 1fa1e7f615 readlinkat: ensure we return ENOENT for the empty pathname for normal lookups
Since the commit below which added O_PATH support to the *at() calls, the
error return for readlink/readlinkat for the empty pathname has switched
from ENOENT to EINVAL:

  commit 65cfc67223
  Author: Al Viro <viro@zeniv.linux.org.uk>
  Date:   Sun Mar 13 15:56:26 2011 -0400

    readlinkat(), fchownat() and fstatat() with empty relative pathnames

This is both unexpected for userspace and makes readlink/readlinkat
inconsistant with all other interfaces; and inconsistant with our stated
return for these pathnames.

As the readlinkat call does not have a flags parameter we cannot use the
AT_EMPTY_PATH approach used in the other calls.  Therefore expose whether
the original path is infact entry via a new user_path_at_empty() path
lookup function.  Use this to determine whether to default to EINVAL or
ENOENT for failures.

Addresses http://bugs.launchpad.net/bugs/817187

[akpm@linux-foundation.org: remove unused getname_flags()]
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
2011-11-02 12:53:42 +01:00