linux-stable.git/fs/xattr.c, branch linux-3.4.y Linux kernel stable tree fs/xattr.c:setxattr(): improve handling of allocation failures 2012-04-05T22:25:50+00:00 Andrew Morton akpm@linux-foundation.org 2012-04-05T21:25:07+00:00 44c824982fd37a578da23cc90885e9690a6a3f0e This allocation can be as large as 64k. - Add __GFP_NOWARN so the a falied kmalloc() is silent - Fall back to vmalloc() if the kmalloc() failed Cc: Dave Chinner <david@fromorbit.com> Cc: Dave Jones <davej@codemonkey.org.uk> Cc: David Rientjes <rientjes@google.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
This allocation can be as large as 64k.

 - Add __GFP_NOWARN so the a falied kmalloc() is silent

 - Fall back to vmalloc() if the kmalloc() failed

Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: David Rientjes <rientjes@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/xattr.c:listxattr(): fall back to vmalloc() if kmalloc() failed 2012-04-05T22:25:50+00:00 Andrew Morton akpm@linux-foundation.org 2012-04-05T21:25:07+00:00 0d08d7b7e13b5060181b11ecdde82d8fda322123 This allocation can be as large as 64k. As David points out, "falling back to vmalloc here is much better solution than failing to retreive the attribute - it will work no matter how fragmented memory gets. That means we don't get incomplete backups occurring after days or months of uptime and successful backups". Cc: Dave Chinner <david@fromorbit.com> Cc: Dave Jones <davej@codemonkey.org.uk> Cc: David Rientjes <rientjes@google.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
This allocation can be as large as 64k.  As David points out, "falling
back to vmalloc here is much better solution than failing to retreive
the attribute - it will work no matter how fragmented memory gets.  That
means we don't get incomplete backups occurring after days or months of
uptime and successful backups".

Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: David Rientjes <rientjes@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/xattr.c: suppress page allocation failure warnings from sys_listxattr() 2012-04-05T22:25:50+00:00 Dave Jones davej@redhat.com 2012-04-05T21:25:06+00:00 703bf2d122c95412a30f72658c53ad6292867b0b This size is user controllable, up to a maximum of XATTR_LIST_MAX (64k). So it's trivial for someone to trigger a stream of order:4 page allocation errors. Signed-off-by: Dave Jones <davej@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Dave Chinner <david@fromorbit.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
This size is user controllable, up to a maximum of XATTR_LIST_MAX (64k).
So it's trivial for someone to trigger a stream of order:4 page
allocation errors.

Signed-off-by: Dave Jones <davej@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dave Chinner <david@fromorbit.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs: reduce the use of module.h wherever possible 2012-02-29T00:31:58+00:00 Paul Gortmaker paul.gortmaker@windriver.com 2011-11-17T04:57:37+00:00 630d9c47274aa89bfa77fe6556d7818bdcb12992 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> 
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>
vfs: mnt_drop_write_file() 2012-01-04T03:52:40+00:00 Al Viro viro@zeniv.linux.org.uk 2011-12-09T13:06:57+00:00 2a79f17e4a641a2f463cb512cb0ec349844a147b new helper (wrapper around mnt_drop_write()) to be used in pair with mnt_want_write_file(). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> 
new helper (wrapper around mnt_drop_write()) to be used in pair with
mnt_want_write_file().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
evm: evm_inode_post_removexattr 2011-07-18T16:29:43+00:00 Mimi Zohar zohar@linux.vnet.ibm.com 2011-03-09T19:39:18+00:00 c7b87de23b6fd5dfbe5c36601f29d6c515056343 When an EVM protected extended attribute is removed, update 'security.evm'. Signed-off-by: Mimi Zohar <zohar@us.ibm.com> Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com> 
When an EVM protected extended attribute is removed, update 'security.evm'.

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com>
xattr: define vfs_getxattr_alloc and vfs_xattr_cmp 2011-07-18T16:29:39+00:00 Mimi Zohar zohar@linux.vnet.ibm.com 2011-03-09T19:23:34+00:00 1601fbad2b14e0b8d4dbb55e749bfe31e972818a vfs_getxattr_alloc() and vfs_xattr_cmp() are two new kernel xattr helper functions. vfs_getxattr_alloc() first allocates memory for the requested xattr and then retrieves it. vfs_xattr_cmp() compares a given value with the contents of an extended attribute. Signed-off-by: Mimi Zohar <zohar@us.ibm.com> Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com> 
vfs_getxattr_alloc() and vfs_xattr_cmp() are two new kernel xattr helper
functions.  vfs_getxattr_alloc() first allocates memory for the requested
xattr and then retrieves it. vfs_xattr_cmp() compares a given value with
the contents of an extended attribute.

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Cache xattr security drop check for write v2 2011-05-28T16:02:09+00:00 Andi Kleen ak@linux.intel.com 2011-05-28T15:25:51+00:00 69b4573296469fd3f70cf7044693074980517067 Some recent benchmarking on btrfs showed that a major scaling bottleneck on large systems on btrfs is currently the xattr lookup on every write. Why xattr lookup on every write I hear you ask? write wants to drop suid and security related xattrs that could set o capabilities for executables. To do that it currently looks up security.capability on EVERY write (even for non executables) to decide whether to drop it or not. In btrfs this causes an additional tree walk, hitting some per file system locks and quite bad scalability. In a simple read workload on a 8S system I saw over 90% CPU time in spinlocks related to that. Chris Mason tells me this is also a problem in ext4, where it hits the global mbcache lock. This patch adds a simple per inode to avoid this problem. We only do the lookup once per file and then if there is no xattr cache the decision. All xattr changes clear the flag. I also used the same flag to avoid the suid check, although that one is pretty cheap. A file system can also set this flag when it creates the inode, if it has a cheap way to do so. This is done for some common file systems in followon patches. With this patch a major part of the lock contention disappears for btrfs. Some testing on smaller systems didn't show significant performance changes, but at least it helps the larger systems and is generally more efficient. v2: Rename is_sgid. add file system helper. Cc: chris.mason@oracle.com Cc: josef@redhat.com Cc: viro@zeniv.linux.org.uk Cc: agruen@linbit.com Cc: Serge E. Hallyn <serue@us.ibm.com> Signed-off-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> 
Some recent benchmarking on btrfs showed that a major scaling bottleneck
on large systems on btrfs is currently the xattr lookup on every write.

Why xattr lookup on every write I hear you ask?

write wants to drop suid and security related xattrs that could set o
capabilities for executables.  To do that it currently looks up
security.capability on EVERY write (even for non executables) to decide
whether to drop it or not.

In btrfs this causes an additional tree walk, hitting some per file system
locks and quite bad scalability. In a simple read workload on a 8S
system I saw over 90% CPU time in spinlocks related to that.

Chris Mason tells me this is also a problem in ext4, where it hits
the global mbcache lock.

This patch adds a simple per inode to avoid this problem.  We only
do the lookup once per file and then if there is no xattr cache
the decision. All xattr changes clear the flag.

I also used the same flag to avoid the suid check, although
that one is pretty cheap.

A file system can also set this flag when it creates the inode,
if it has a cheap way to do so.  This is done for some common file systems
in followon patches.

With this patch a major part of the lock contention disappears
for btrfs. Some testing on smaller systems didn't show significant
performance changes, but at least it helps the larger systems
and is generally more efficient.

v2: Rename is_sgid. add file system helper.
Cc: chris.mason@oracle.com
Cc: josef@redhat.com
Cc: viro@zeniv.linux.org.uk
Cc: agruen@linbit.com
Cc: Serge E. Hallyn <serue@us.ibm.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
xattr: Fix error results for non-existent / invisible attributes 2011-05-27T13:43:00+00:00 Andreas Gruenbacher agruen@kernel.org 2011-05-27T12:50:36+00:00 55b23bde19c08f14127a27d461a4e079942c7258 Return -ENODATA when trying to read a user.* attribute which cannot exist: user space otherwise does not have a reasonable way to distinguish between non-existent and inaccessible attributes. Likewise, return -ENODATA when an unprivileged process tries to read a trusted.* attribute: to unprivileged processes, those attributes are invisible (listxattr() won't include them). Related to this bug report: https://bugzilla.redhat.com/660613 Signed-off-by: Andreas Gruenbacher <agruen@kernel.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> 
Return -ENODATA when trying to read a user.* attribute which cannot
exist: user space otherwise does not have a reasonable way to
distinguish between non-existent and inaccessible attributes.

Likewise, return -ENODATA when an unprivileged process tries to read a
trusted.* attribute: to unprivileged processes, those attributes are
invisible (listxattr() won't include them).

Related to this bug report: https://bugzilla.redhat.com/660613

Signed-off-by: Andreas Gruenbacher <agruen@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
vfs: Pass setxattr(2) flags properly 2011-04-21T14:34:44+00:00 Jan Kara jack@suse.cz 2011-04-20T18:30:40+00:00 df7e130384efd1c732aa08648dad46687fee3d96 For some reason generic_setxattr() did not pass flags (XATTR_CREATE, XATTR_REPLACE) to the filesystem specific helper. This caused that setxattr(2) syscall just ignored these flags. Fix the bug by passing flags correctly. Signed-off-by: Jan Kara <jack@suse.cz> Acked-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
For some reason generic_setxattr() did not pass flags (XATTR_CREATE,
XATTR_REPLACE) to the filesystem specific helper. This caused that
setxattr(2) syscall just ignored these flags.

Fix the bug by passing flags correctly.

Signed-off-by: Jan Kara <jack@suse.cz>
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>