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path: root/fs/proc_namespace.c
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* vfs: add support for a lazytime mount optionTheodore Ts'o2015-02-051-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | Add a new mount option which enables a new "lazytime" mode. This mode causes atime, mtime, and ctime updates to only be made to the in-memory version of the inode. The on-disk times will only get updated when (a) if the inode needs to be updated for some non-time related change, (b) if userspace calls fsync(), syncfs() or sync(), or (c) just before an undeleted inode is evicted from memory. This is OK according to POSIX because there are no guarantees after a crash unless userspace explicitly requests via a fsync(2) call. For workloads which feature a large number of random write to a preallocated file, the lazytime mount option significantly reduces writes to the inode table. The repeated 4k writes to a single block will result in undesirable stress on flash devices and SMR disk drives. Even on conventional HDD's, the repeated writes to the inode table block will trigger Adjacent Track Interference (ATI) remediation latencies, which very negatively impact long tail latencies --- which is a very big deal for web serving tiers (for example). Google-Bug-Id: 18297052 Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* vfs: make mounts and mountstats honor root dir like mountinfo doesDmitry V. Levin2014-12-171-2/+11
| | | | | | | | | As we already show mountpoints relative to the root directory, thanks to the change made back in 2000, change show_vfsmnt() and show_vfsstat() to skip out-of-root mountpoints the same way as show_mountinfo() does. Signed-off-by: Dmitry V. Levin <ldv@altlinux.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* vfs: cleanup show_mountinfoDmitry V. Levin2014-12-171-2/+1
| | | | | | | | | | | | Starting with commit v3.2-rc4-1-g02125a8, seq_path_root() no longer changes the value of its "struct path *root" argument. Starting with commit v3.2-rc7-104-g8c9379e, the "struct path *root" argument of seq_path_root() is const. As result, the temporary variable "root" in show_mountinfo() that holds a copy of struct path root is no longer needed. Signed-off-by: Dmitry V. Levin <ldv@altlinux.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* namespaces: Use task_lock and not rcu to protect nsproxyEric W. Biederman2014-07-291-5/+3
| | | | | | | | | | | | | | | | | | | | | | The synchronous syncrhonize_rcu in switch_task_namespaces makes setns a sufficiently expensive system call that people have complained. Upon inspect nsproxy no longer needs rcu protection for remote reads. remote reads are rare. So optimize for same process reads and write by switching using rask_lock instead. This yields a simpler to understand lock, and a faster setns system call. In particular this fixes a performance regression observed by Rafael David Tinoco <rafael.tinoco@canonical.com>. This is effectively a revert of Pavel Emelyanov's commit cf7b708c8d1d7a27736771bcf4c457b332b0f818 Make access to task's nsproxy lighter from 2007. The race this originialy fixed no longer exists as do_notify_parent uses task_active_pid_ns(parent) instead of parent->nsproxy. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* reduce m_start() cost...Al Viro2014-04-011-0/+1
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* fs/proc_namespace.c: simplify testing nsp and nsp->mnt_nsAxel Lin2014-01-231-6/+1
| | | | | | | | Trivial cleanup to eliminate a goto. Signed-off-by: Axel Lin <axel.lin@ingics.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* don't bother with vfsmount_lock in mounts_poll()Al Viro2013-10-241-4/+4
| | | | | | | wake_up_interruptible/poll_wait provide sufficient barriers; just use ACCESS_ONCE() to fetch ns->event and that's it. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* get rid of magic in proc_namespace.cAl Viro2012-07-141-4/+3
| | | | | | | | don't rely on proc_mounts->m being the first field; container_of() is there for purpose. No need to bother with ->private, while we are at it - the same container_of will do nicely. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* brlocks/lglocks: API cleanupsAndi Kleen2012-05-291-2/+2
| | | | | | | | | | | | | | | | | | | | | lglocks and brlocks are currently generated with some complicated macros in lglock.h. But there's no reason to not just use common utility functions and put all the data into a common data structure. In preparation, this patch changes the API to look more like normal function calls with pointers, not magic macros. The patch is rather large because I move over all users in one go to keep it bisectable. This impacts the VFS somewhat in terms of lines changed. But no actual behaviour change. [akpm@linux-foundation.org: checkpatch fixes] Signed-off-by: Andi Kleen <ak@linux.intel.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* vfs: switch ->show_options() to struct dentry *Al Viro2012-01-061-2/+2
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* vfs: switch ->show_path() to struct dentry *Al Viro2012-01-061-1/+1
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* vfs: switch ->show_devname() to struct dentry *Al Viro2012-01-061-8/+9
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* vfs: switch ->show_stats to struct dentry *Al Viro2012-01-061-5/+6
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* vfs: take /proc/*/mounts and friends to fs/proc_namespace.cAl Viro2012-01-031-0/+331
rationale: that stuff is far tighter bound to fs/namespace.c than to the guts of procfs proper. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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