user/sven/linux.git/include/linux/fs.h, branch v3.2

vmscan: use atomic-long for shrinker batching

2011-12-09T15:50:27Z

Use atomic-long operations instead of looping around cmpxchg(). [akpm@linux-foundation.org: massage atomic.h inclusions] Signed-off-by: Konstantin Khlebnikov Cc: Dave Chinner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

fix apparmor dereferencing potentially freed dentry, sanitize __d_path() API

2011-12-07T04:57:18Z

__d_path() API is asking for trouble and in case of apparmor d_namespace_path() getting just that. The root cause is that when __d_path() misses the root it had been told to look for, it stores the location of the most remote ancestor in *root. Without grabbing references. Sure, at the moment of call it had been pinned down by what we have in *path. And if we raced with umount -l, we could have very well stopped at vfsmount/dentry that got freed as soon as prepend_path() dropped vfsmount_lock. It is safe to compare these pointers with pre-existing (and known to be still alive) vfsmount and dentry, as long as all we are asking is "is it the same address?". Dereferencing is not safe and apparmor ended up stepping into that. d_namespace_path() really wants to examine the place where we stopped, even if it's not connected to our namespace. As the result, it looked at ->d_sb->s_magic of a dentry that might've been already freed by that point. All other callers had been careful enough to avoid that, but it's really a bad interface - it invites that kind of trouble. The fix is fairly straightforward, even though it's bigger than I'd like: * prepend_path() root argument becomes const. * __d_path() is never called with NULL/NULL root. It was a kludge to start with. Instead, we have an explicit function - d_absolute_root(). Same as __d_path(), except that it doesn't get root passed and stops where it stops. apparmor and tomoyo are using it. * __d_path() returns NULL on path outside of root. The main caller is show_mountinfo() and that's precisely what we pass root for - to skip those outside chroot jail. Those who don't want that can (and do) use d_path(). * __d_path() root argument becomes const. Everyone agrees, I hope. * apparmor does *NOT* try to use __d_path() or any of its variants when it sees that path->mnt is an internal vfsmount. In that case it's definitely not mounted anywhere and dentry_path() is exactly what we want there. Handling of sysctl()-triggered weirdness is moved to that place. * if apparmor is asked to do pathname relative to chroot jail and __d_path() tells it we it's not in that jail, the sucker just calls d_absolute_path() instead. That's the other remaining caller of __d_path(), BTW. * seq_path_root() does _NOT_ return -ENAMETOOLONG (it's stupid anyway - the normal seq_file logics will take care of growing the buffer and redoing the call of ->show() just fine). However, if it gets path not reachable from root, it returns SEQ_SKIP. The only caller adjusted (i.e. stopped ignoring the return value as it used to do). Reviewed-by: John Johansen ACKed-by: John Johansen Signed-off-by: Al Viro Cc: stable@vger.kernel.org

new helper: mount_subtree()

2011-11-17T03:00:34Z

takes vfsmount and relative path, does lookup within that vfsmount (possibly triggering automounts) and returns the result as root of subtree suitable for return by ->mount() (i.e. a reference to dentry and an active reference to its superblock grabbed, superblock locked exclusive). btrfs and nfs switched to it instead of open-coding the sucker. Signed-off-by: Al Viro

Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/hch/vfs-queue

2011-11-02T18:41:01Z

* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/hch/vfs-queue: vfs: add d_prune dentry operation vfs: protect i_nlink filesystems: add set_nlink() filesystems: add missing nlink wrappers logfs: remove unnecessary nlink setting ocfs2: remove unnecessary nlink setting jfs: remove unnecessary nlink setting hypfs: remove unnecessary nlink setting vfs: ignore error on forced remount readlinkat: ensure we return ENOENT for the empty pathname for normal lookups vfs: fix dentry leak in simple_fill_super()

Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

2011-11-02T17:06:20Z

* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (97 commits) jbd2: Unify log messages in jbd2 code jbd/jbd2: validate sb->s_first in journal_get_superblock() ext4: let ext4_ext_rm_leaf work with EXT_DEBUG defined ext4: fix a syntax error in ext4_ext_insert_extent when debugging enabled ext4: fix a typo in struct ext4_allocation_context ext4: Don't normalize an falloc request if it can fit in 1 extent. ext4: remove comments about extent mount option in ext4_new_inode() ext4: let ext4_discard_partial_buffers handle unaligned range correctly ext4: return ENOMEM if find_or_create_pages fails ext4: move vars to local scope in ext4_discard_partial_page_buffers_no_lock() ext4: Create helper function for EXT4_IO_END_UNWRITTEN and i_aiodio_unwritten ext4: optimize locking for end_io extent conversion ext4: remove unnecessary call to waitqueue_active() ext4: Use correct locking for ext4_end_io_nolock() ext4: fix race in xattr block allocation path ext4: trace punch_hole correctly in ext4_ext_map_blocks ext4: clean up AGGRESSIVE_TEST code ext4: move variables to their scope ext4: fix quota accounting during migration ext4: migrate cleanup ...

vfs: protect i_nlink

2011-11-02T11:53:43Z

Prevent direct modification of i_nlink by making it const and adding a non-const __i_nlink alias. Signed-off-by: Miklos Szeredi Tested-by: Toshiyuki Okajima Signed-off-by: Christoph Hellwig

filesystems: add set_nlink()

2011-11-02T11:53:43Z

Replace remaining direct i_nlink updates with a new set_nlink() updater function. Signed-off-by: Miklos Szeredi Tested-by: Toshiyuki Okajima Signed-off-by: Christoph Hellwig

treewide: use printf not attribute__((format(printf,...)))

2011-11-01T00:30:54Z

Standardize the style for compiler based printf format verification. Standardized the location of __printf too. Done via script and a little typing. $ grep -rPl --include=*.[ch] -w "__attribute__" * | \ grep -vP "^(tools|scripts|include/linux/compiler-gcc.h)" | \ xargs perl -n -i -e 'local $/; while (<>) { s/\b__attribute__\s*$\s*\(\s*format\s*\(\s*printf\s*,\s*(.+)\s*,\s*(.+)\s*$\s*\)\s*\)/__printf($1, $2)/g ; print; }' [akpm@linux-foundation.org: revert arch bits] Signed-off-by: Joe Perches Cc: "Kirill A. Shutemov" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Cross Memory Attach

2011-11-01T00:30:44Z

The basic idea behind cross memory attach is to allow MPI programs doing intra-node communication to do a single copy of the message rather than a double copy of the message via shared memory. The following patch attempts to achieve this by allowing a destination process, given an address and size from a source process, to copy memory directly from the source process into its own address space via a system call. There is also a symmetrical ability to copy from the current process's address space into a destination process's address space. - Use of /proc/pid/mem has been considered, but there are issues with using it: - Does not allow for specifying iovecs for both src and dest, assuming preadv or pwritev was implemented either the area read from or written to would need to be contiguous. - Currently mem_read allows only processes who are currently ptrace'ing the target and are still able to ptrace the target to read from the target. This check could possibly be moved to the open call, but its not clear exactly what race this restriction is stopping (reason appears to have been lost) - Having to send the fd of /proc/self/mem via SCM_RIGHTS on unix domain socket is a bit ugly from a userspace point of view, especially when you may have hundreds if not (eventually) thousands of processes that all need to do this with each other - Doesn't allow for some future use of the interface we would like to consider adding in the future (see below) - Interestingly reading from /proc/pid/mem currently actually involves two copies! (But this could be fixed pretty easily) As mentioned previously use of vmsplice instead was considered, but has problems. Since you need the reader and writer working co-operatively if the pipe is not drained then you block. Which requires some wrapping to do non blocking on the send side or polling on the receive. In all to all communication it requires ordering otherwise you can deadlock. And in the example of many MPI tasks writing to one MPI task vmsplice serialises the copying. There are some cases of MPI collectives where even a single copy interface does not get us the performance gain we could. For example in an MPI_Reduce rather than copy the data from the source we would like to instead use it directly in a mathops (say the reduce is doing a sum) as this would save us doing a copy. We don't need to keep a copy of the data from the source. I haven't implemented this, but I think this interface could in the future do all this through the use of the flags - eg could specify the math operation and type and the kernel rather than just copying the data would apply the specified operation between the source and destination and store it in the destination. Although we don't have a "second user" of the interface (though I've had some nibbles from people who may be interested in using it for intra process messaging which is not MPI). This interface is something which hardware vendors are already doing for their custom drivers to implement fast local communication. And so in addition to this being useful for OpenMPI it would mean the driver maintainers don't have to fix things up when the mm changes. There was some discussion about how much faster a true zero copy would go. Here's a link back to the email with some testing I did on that: http://marc.info/?l=linux-mm&m=130105930902915&w=2 There is a basic man page for the proposed interface here: http://ozlabs.org/~cyeoh/cma/process_vm_readv.txt This has been implemented for x86 and powerpc, other architecture should mainly (I think) just need to add syscall numbers for the process_vm_readv and process_vm_writev. There are 32 bit compatibility versions for 64-bit kernels. For arch maintainers there are some simple tests to be able to quickly verify that the syscalls are working correctly here: http://ozlabs.org/~cyeoh/cma/cma-test-20110718.tgz Signed-off-by: Chris Yeoh Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: Thomas Gleixner Cc: Arnd Bergmann Cc: Paul Mackerras Cc: Benjamin Herrenschmidt Cc: David Howells Cc: James Morris Cc: Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

fs: optimize out 16 bytes worth of padding in struct inode

2011-10-29T12:24:18Z

Rearrange the fields in struct inode so that on an x86_64 system, fields that require 8-byte alignment don't end up causing 4-byte holes in the structure. It reduces the size of struct inode from 568 bytes to 552 bytes. Also move the fields protected by i_lock (i_blocks, i_bytes, and i_size) into the same cache line as i_lock. Signed-off-by: "Theodore Ts'o"