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2016-04-04mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macrosKirill A. Shutemov1-3/+3
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>
2016-01-19pipe: limit the per-user amount of pages allocated in pipesWilly Tarreau1-2/+45
On no-so-small systems, it is possible for a single process to cause an OOM condition by filling large pipes with data that are never read. A typical process filling 4000 pipes with 1 MB of data will use 4 GB of memory. On small systems it may be tricky to set the pipe max size to prevent this from happening. This patch makes it possible to enforce a per-user soft limit above which new pipes will be limited to a single page, effectively limiting them to 4 kB each, as well as a hard limit above which no new pipes may be created for this user. This has the effect of protecting the system against memory abuse without hurting other users, and still allowing pipes to work correctly though with less data at once. The limit are controlled by two new sysctls : pipe-user-pages-soft, and pipe-user-pages-hard. Both may be disabled by setting them to zero. The default soft limit allows the default number of FDs per process (1024) to create pipes of the default size (64kB), thus reaching a limit of 64MB before starting to create only smaller pipes. With 256 processes limited to 1024 FDs each, this results in 1024*64kB + (256*1024 - 1024) * 4kB = 1084 MB of memory allocated for a user. The hard limit is disabled by default to avoid breaking existing applications that make intensive use of pipes (eg: for splicing). Reported-by: socketpair@gmail.com Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Mitigates: CVE-2013-4312 (Linux 2.0+) Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-11-11fs/pipe.c: return error code rather than 0 in pipe_write()Eric Biggers1-5/+4
pipe_write() would return 0 if it failed to merge the beginning of the data to write with the last, partially filled pipe buffer. It should return an error code instead. Userspace programs could be confused by write() returning 0 when called with a nonzero 'count'. The EFAULT error case was a regression from f0d1bec9d5 ("new helper: copy_page_from_iter()"), while the ops->confirm() error case was a much older bug. Test program: #include <assert.h> #include <errno.h> #include <unistd.h> int main(void) { int fd[2]; char data[1] = {0}; assert(0 == pipe(fd)); assert(1 == write(fd[1], data, 1)); /* prior to this patch, write() returned 0 here */ assert(-1 == write(fd[1], NULL, 1)); assert(errno == EFAULT); } Cc: stable@vger.kernel.org # at least v3.15+ Signed-off-by: Eric Biggers <ebiggers3@gmail.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-11-11fs/pipe.c: preserve alloc_file() error codeEric Biggers1-3/+6
If sys_pipe() was unable to allocate a 'struct file', it always failed with ENFILE, which means "The number of simultaneously open files in the system would exceed a system-imposed limit." However, alloc_file() actually returns an ERR_PTR value and might fail with other error codes. Currently, in addition to ENFILE, it can fail with ENOMEM, potentially when there are few open files in the system. Update sys_pipe() to preserve this error code. In a prior submission of a similar patch (1) some concern was raised about introducing a new error code for sys_pipe(). However, for most system calls, programs cannot assume that new error codes will never be introduced. In addition, ENOMEM was, in fact, already a possible error code for sys_pipe(), in the case where the file descriptor table could not be expanded due to insufficient memory. (1) http://comments.gmane.org/gmane.linux.kernel/1357942 Signed-off-by: Eric Biggers <ebiggers3@gmail.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-04-15VFS: assorted weird filesystems: d_inode() annotationsDavid Howells1-1/+1
Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-04-11make new_sync_{read,write}() staticAl Viro1-2/+0
All places outside of core VFS that checked ->read and ->write for being NULL or called the methods directly are gone now, so NULL {read,write} with non-NULL {read,write}_iter will do the right thing in all cases. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-03-25fs: move struct kiocb to fs.hChristoph Hellwig1-1/+0
struct kiocb now is a generic I/O container, so move it to fs.h. Also do a #include diet for aio.h while we're at it. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-05-06new helper: copy_page_from_iter()Al Viro1-110/+19
parallel to copy_page_to_iter(). pipe_write() switched to it (and became ->write_iter()). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-05-06pipe: switch to ->read_iter()Al Viro1-11/+5
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-05-06start adding the tag to iov_iterAl Viro1-1/+1
For now, just use the same thing we pass to ->direct_IO() - it's all iovec-based at the moment. Pass it explicitly to iov_iter_init() and account for kvec vs. iovec in there, by the same kludge NFS ->direct_IO() uses. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-04-01switch pipe_read() to copy_page_to_iter()Al Viro1-71/+8
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-04-01pipe: kill ->map() and ->unmap()Al Viro1-54/+16
all pipe_buffer_operations have the same instances of those... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-01-23fs/pipe.c: skip file_update_time on frozen fsDmitry Monakhov1-1/+2
Pipe has no data associated with fs so it is not good idea to block pipe_write() if FS is frozen, but we can not update file's time on such filesystem. Let's use same idea as we use in touch_time(). Addresses https://bugzilla.kernel.org/show_bug.cgi?id=65701 Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org> Reviewed-by: Jan Kara <jack@suse.cz> 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>
2013-12-02vfs: fix subtle use-after-free of pipe_inode_infoLinus Torvalds1-20/+19
The pipe code was trying (and failing) to be very careful about freeing the pipe info only after the last access, with a pattern like: spin_lock(&inode->i_lock); if (!--pipe->files) { inode->i_pipe = NULL; kill = 1; } spin_unlock(&inode->i_lock); __pipe_unlock(pipe); if (kill) free_pipe_info(pipe); where the final freeing is done last. HOWEVER. The above is actually broken, because while the freeing is done at the end, if we have two racing processes releasing the pipe inode info, the one that *doesn't* free it will decrement the ->files count, and unlock the inode i_lock, but then still use the "pipe_inode_info" afterwards when it does the "__pipe_unlock(pipe)". This is *very* hard to trigger in practice, since the race window is very small, and adding debug options seems to just hide it by slowing things down. Simon originally reported this way back in July as an Oops in kmem_cache_allocate due to a single bit corruption (due to the final "spin_unlock(pipe->mutex.wait_lock)" incrementing a field in a different allocation that had re-used the free'd pipe-info), it's taken this long to figure out. Since the 'pipe->files' accesses aren't even protected by the pipe lock (we very much use the inode lock for that), the simple solution is to just drop the pipe lock early. And since there were two users of this pattern, create a helper function for it. Introduced commit ba5bb147330a ("pipe: take allocation and freeing of pipe_inode_info out of ->i_mutex"). Reported-by: Simon Kirby <sim@hostway.ca> Reported-by: Ian Applegate <ia@cloudflare.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Cc: stable@kernel.org # v3.10+ Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-05-07aio: don't include aio.h in sched.hKent Overstreet1-0/+1
Faster kernel compiles by way of fewer unnecessary includes. [akpm@linux-foundation.org: fix fallout] [akpm@linux-foundation.org: fix build] Signed-off-by: Kent Overstreet <koverstreet@google.com> Cc: Zach Brown <zab@redhat.com> Cc: Felipe Balbi <balbi@ti.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Jens Axboe <axboe@kernel.dk> Cc: Asai Thambi S P <asamymuthupa@micron.com> Cc: Selvan Mani <smani@micron.com> Cc: Sam Bradshaw <sbradshaw@micron.com> Cc: Jeff Moyer <jmoyer@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Benjamin LaHaise <bcrl@kvack.org> Reviewed-by: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-09get rid of the last free_pipe_info() callersAl Viro1-12/+6
and rename __free_pipe_info() to free_pipe_info() Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-04-09get rid of alloc_pipe_info() argumentAl Viro1-3/+3
not used anymore Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-04-09get rid of pipe->inodeAl Viro1-3/+2
it's used only as a flag to distinguish normal pipes/FIFOs from the internal per-task one used by file-to-file splice. And pipe->files would work just as well for that purpose... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-04-09introduce variants of pipe_lock/pipe_unlock for real pipes/FIFOsAl Viro1-15/+25
fs/pipe.c file_operations methods *know* that pipe is not an internal one; no need to check pipe->inode for those callers. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-04-09pipe: set file->private_data to ->i_pipeAl Viro1-8/+9
simplify get_pipe_info(), while we are at it Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-04-09pipe: don't use ->i_mutexAl Viro1-2/+3
now it can be done - put mutex into pipe_inode_info, use it instead of ->i_mutex Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-04-09pipe: take allocation and freeing of pipe_inode_info out of ->i_mutexAl Viro1-21/+51
* new field - pipe->files; number of struct file over that pipe (all sharing the same inode, of course); protected by inode->i_lock. * pipe_release() decrements pipe->files, clears inode->i_pipe when if the counter has reached 0 (all under ->i_lock) and, in that case, frees pipe after having done pipe_unlock() * fifo_open() starts with grabbing ->i_lock, and either bumps pipe->files if ->i_pipe was non-NULL or allocates a new pipe (dropping and regaining ->i_lock) and rechecks ->i_pipe; if it's still NULL, inserts new pipe there, otherwise bumps ->i_pipe->files and frees the one we'd allocated. At that point we know that ->i_pipe is non-NULL and won't go away, so we can do pipe_lock() on it and proceed as we used to. If we end up failing, decrement pipe->files and if it reaches 0 clear ->i_pipe and free the sucker after pipe_unlock(). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-04-09pipe: preparation to new locking rulesAl Viro1-23/+15
* use the fact that file_inode(file)->i_pipe doesn't change while the file is opened - no locks needed to access that. * switch to pipe_lock/pipe_unlock where it's easy to do Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-04-09pipe: switch wait_for_partner() and wake_up_partner() to pipe_inode_infoAl Viro1-9/+9
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-04-09pipe: fold file_operations instances in oneAl Viro1-189/+32
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-04-09fold fifo.c into pipe.cAl Viro1-0/+138
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-03-12vfs: fix pipe counter breakageAl Viro1-0/+3
If you open a pipe for neither read nor write, the pipe code will not add any usage counters to the pipe, causing the 'struct pipe_inode_info" to be potentially released early. That doesn't normally matter, since you cannot actually use the pipe, but the pipe release code - particularly fasync handling - still expects the actual pipe infrastructure to all be there. And rather than adding NULL pointer checks, let's just disallow this case, the same way we already do for the named pipe ("fifo") case. This is ancient going back to pre-2.4 days, and until trinity, nobody naver noticed. Reported-by: Dave Jones <davej@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-22fs: Preserve error code in get_empty_filp(), part 2Anatol Pomozov1-2/+2
Allocating a file structure in function get_empty_filp() might fail because of several reasons: - not enough memory for file structures - operation is not allowed - user is over its limit Currently the function returns NULL in all cases and we loose the exact reason of the error. All callers of get_empty_filp() assume that the function can fail with ENFILE only. Return error through pointer. Change all callers to preserve this error code. [AV: cleaned up a bit, carved the get_empty_filp() part out into a separate commit (things remaining here deal with alloc_file()), removed pipe(2) behaviour change] Signed-off-by: Anatol Pomozov <anatol.pomozov@gmail.com> Reviewed-by: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-22new helper: file_inode(file)Al Viro1-8/+8
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-09-26pipe(2) - race-free error recoveryAl Viro1-9/+22
don't mess with sys_close() if copy_to_user() fails; just postpone fd_install() until we know it hasn't. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-08-01Merge branch 'for-linus' of ↵Linus Torvalds1-49/+26
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull second vfs pile from Al Viro: "The stuff in there: fsfreeze deadlock fixes by Jan (essentially, the deadlock reproduced by xfstests 068), symlink and hardlink restriction patches, plus assorted cleanups and fixes. Note that another fsfreeze deadlock (emergency thaw one) is *not* dealt with - the series by Fernando conflicts a lot with Jan's, breaks userland ABI (FIFREEZE semantics gets changed) and trades the deadlock for massive vfsmount leak; this is going to be handled next cycle. There probably will be another pull request, but that stuff won't be in it." Fix up trivial conflicts due to unrelated changes next to each other in drivers/{staging/gdm72xx/usb_boot.c, usb/gadget/storage_common.c} * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (54 commits) delousing target_core_file a bit Documentation: Correct s_umount state for freeze_fs/unfreeze_fs fs: Remove old freezing mechanism ext2: Implement freezing btrfs: Convert to new freezing mechanism nilfs2: Convert to new freezing mechanism ntfs: Convert to new freezing mechanism fuse: Convert to new freezing mechanism gfs2: Convert to new freezing mechanism ocfs2: Convert to new freezing mechanism xfs: Convert to new freezing code ext4: Convert to new freezing mechanism fs: Protect write paths by sb_start_write - sb_end_write fs: Skip atime update on frozen filesystem fs: Add freezing handling to mnt_want_write() / mnt_drop_write() fs: Improve filesystem freezing handling switch the protection of percpu_counter list to spinlock nfsd: Push mnt_want_write() outside of i_mutex btrfs: Push mnt_want_write() outside of i_mutex fat: Push mnt_want_write() outside of i_mutex ...
2012-07-29consolidate pipe file creationAl Viro1-49/+26
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-07-24pipe: remove KM_USER0 from commentsCong Wang1-1/+1
Signed-off-by: Cong Wang <amwang@redhat.com>
2012-06-01fs: introduce inode operation ->update_timeJosef Bacik1-2/+5
Btrfs has to make sure we have space to allocate new blocks in order to modify the inode, so updating time can fail. We've gotten around this by having our own file_update_time but this is kind of a pain, and Christoph has indicated he would like to make xfs do something different with atime updates. So introduce ->update_time, where we will deal with i_version an a/m/c time updates and indicate which changes need to be made. The normal version just does what it has always done, updates the time and marks the inode dirty, and then filesystems can choose to do something different. I've gone through all of the users of file_update_time and made them check for errors with the exception of the fault code since it's complicated and I wasn't quite sure what to do there, also Jan is going to be pushing the file time updates into page_mkwrite for those who have it so that should satisfy btrfs and make it not a big deal to check the file_update_time() return code in the generic fault path. Thanks, Signed-off-by: Josef Bacik <josef@redhat.com>
2012-05-30pipe: return -ENOIOCTLCMD instead of -EINVAL on unknown ioctl commandWill Deacon1-1/+1
As described in commit 07d106d0a ("vfs: fix up ENOIOCTLCMD error handling"), drivers should return -ENOIOCTLCMD if they receive an ioctl command which they don't understand. Doing so will result in -ENOTTY being returned to userspace, which matches the behaviour of the compat layer if it fails to translate an ioctl command. This patch fixes the pipe ioctl to return -ENOIOCTLCMD instead of -EINVAL when passed an unknown ioctl command. Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-04-29pipes: add a "packetized pipe" mode for writingLinus Torvalds1-2/+29
The actual internal pipe implementation is already really about individual packets (called "pipe buffers"), and this simply exposes that as a special packetized mode. When we are in the packetized mode (marked by O_DIRECT as suggested by Alan Cox), a write() on a pipe will not merge the new data with previous writes, so each write will get a pipe buffer of its own. The pipe buffer is then marked with the PIPE_BUF_FLAG_PACKET flag, which in turn will tell the reader side to break the read at that boundary (and throw away any partial packet contents that do not fit in the read buffer). End result: as long as you do writes less than PIPE_BUF in size (so that the pipe doesn't have to split them up), you can now treat the pipe as a packet interface, where each read() system call will read one packet at a time. You can just use a sufficiently big read buffer (PIPE_BUF is sufficient, since bigger than that doesn't guarantee atomicity anyway), and the return value of the read() will naturally give you the size of the packet. NOTE! We do not support zero-sized packets, and zero-sized reads and writes to a pipe continue to be no-ops. Also note that big packets will currently be split at write time, but that the size at which that happens is not really specified (except that it's bigger than PIPE_BUF). Currently that limit is the system page size, but we might want to explicitly support bigger packets some day. The main user for this is going to be the autofs packet interface, allowing us to stop having to care so deeply about exact packet sizes (which have had bugs with 32/64-bit compatibility modes). But user space can create packetized pipes with "pipe2(fd, O_DIRECT)", which will fail with an EINVAL on kernels that do not support this interface. Tested-by: Michael Tokarev <mjt@tls.msk.ru> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: David Miller <davem@davemloft.net> Cc: Ian Kent <raven@themaw.net> Cc: Thomas Meyer <thomas@m3y3r.de> Cc: stable@kernel.org # needed for systemd/autofs interaction fix Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-23magic.h: move some FS magic numbers into magic.hMuthu Kumar1-0/+1
- Move open-coded filesystem magic numbers into magic.h - Rearrange magic.h so that the filesystem-related constants are grouped together. Signed-off-by: Muthukumar R <muthur@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-20fs: remove the second argument of k[un]map_atomic()Cong Wang1-4/+4
Acked-by: Benjamin LaHaise <bcrl@kvack.org> Signed-off-by: Cong Wang <amwang@redhat.com>
2012-01-12pipe: fail cleanly when root tries F_SETPIPE_SZ with big sizeSasha Levin1-1/+1
When a user with the CAP_SYS_RESOURCE cap tries to F_SETPIPE_SZ a pipe with size bigger than kmalloc() can alloc it spits out an ugly warning: ------------[ cut here ]------------ WARNING: at mm/page_alloc.c:2095 __alloc_pages_nodemask+0x5d3/0x7a0() Pid: 733, comm: a.out Not tainted 3.2.0-rc1+ #4 Call Trace: warn_slowpath_common+0x75/0xb0 warn_slowpath_null+0x15/0x20 __alloc_pages_nodemask+0x5d3/0x7a0 __get_free_pages+0x12/0x50 __kmalloc+0x12b/0x150 pipe_set_size+0x75/0x120 pipe_fcntl+0xf8/0x140 do_fcntl+0x2d4/0x410 sys_fcntl+0x66/0xa0 system_call_fastpath+0x16/0x1b ---[ end trace 432f702e6db7b5ee ]--- Instead, make kcalloc() handle the overflow case and fail quietly. [akpm@linux-foundation.org: switch to sizeof(*bufs) for 80-column niceness] Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Acked-by: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-01-03vfs: pipe.c is really non-modularAl Viro1-7/+0
... so no exitcalls there. Not much would work if pipe(2) would stop working, after all... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-10-31fs/pipe.c: add ->statfs callback for pipefsPavel Emelyanov1-0/+1
Currently a statfs on a pipe's /proc/<pid>/fd/ link returns -ENOSYS. Wire pipfs up so that the statfs succeeds. This is required by checkpoint-restart in the userspace to make it possible to distinguish pipes from fifos. When we dump information about task's open files we use the /proc/pid/fd directoy's symlinks and the fact that opening any of them gives us exactly the same dentry->inode pair as the original process has. Now if a task we're dumping has opened pipe and fifo we need to detect this and act accordingly. Knowing that an fd with type S_ISFIFO resides on a pipefs is the most precise way. Signed-off-by: Pavel Emelyanov <xemul@parallels.com> Reviewed-by: Tejun Heo <tj@kernel.org> Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org> 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>
2011-07-26vfs: dont chain pipe/anon/socket on superblock s_inodes listEric Dumazet1-1/+1
Workloads using pipes and sockets hit inode_sb_list_lock contention. superblock s_inodes list is needed for quota, dirty, pagecache and fsnotify management. pipe/anon/socket fs are clearly not candidates for these. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-07-24VFS : mount lock scalability for internal mountsTim Chen1-1/+1
For a number of file systems that don't have a mount point (e.g. sockfs and pipefs), they are not marked as long term. Therefore in mntput_no_expire, all locks in vfs_mount lock are taken instead of just local cpu's lock to aggregate reference counts when we release reference to file objects. In fact, only local lock need to have been taken to update ref counts as these file systems are in no danger of going away until we are ready to unregister them. The attached patch marks file systems using kern_mount without mount point as long term. The contentions of vfs_mount lock is now eliminated. Before un-registering such file system, kern_unmount should be called to remove the long term flag and make the mount point ready to be freed. Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-01-20Fix broken "pipe: use event aware wakeups" optimizationLinus Torvalds1-5/+5
Commit e462c448fdc8 ("pipe: use event aware wakeups") optimized the pipe event wakeup calls to avoid wakeups if the events do not match the requested set. However, the optimization was buggy, in that it didn't actually use the correct sets for the events: when we make room for more data to be written, the pipe poll() routine will return both the POLLOUT _and_ POLLWRNORM bits. Similarly for read. And most critically, when a pipe is released, that will potentially result in POLLHUP|POLLERR (depending on whether it was the last reader or writer), not just the regular POLLIN|POLLOUT. This bug showed itself as a hung gnome-screensaver-dialog process, stuck forever (or at least until it was poked by a signal or by being traced) in a poll() system call. Cc: Davide Libenzi <davidel@xmailserver.org> Cc: David S. Miller <davem@davemloft.net> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-01-16sanitize vfsmount refcounting changesAl Viro1-1/+1
Instead of splitting refcount between (per-cpu) mnt_count and (SMP-only) mnt_longrefs, make all references contribute to mnt_count again and keep track of how many are longterm ones. Accounting rules for longterm count: * 1 for each fs_struct.root.mnt * 1 for each fs_struct.pwd.mnt * 1 for having non-NULL ->mnt_ns * decrement to 0 happens only under vfsmount lock exclusive That allows nice common case for mntput() - since we can't drop the final reference until after mnt_longterm has reached 0 due to the rules above, mntput() can grab vfsmount lock shared and check mnt_longterm. If it turns out to be non-zero (which is the common case), we know that this is not the final mntput() and can just blindly decrement percpu mnt_count. Otherwise we grab vfsmount lock exclusive and do usual decrement-and-check of percpu mnt_count. For fs_struct.c we have mnt_make_longterm() and mnt_make_shortterm(); namespace.c uses the latter in places where we don't already hold vfsmount lock exclusive and opencodes a few remaining spots where we need to manipulate mnt_longterm. Note that we mostly revert the code outside of fs/namespace.c back to what we used to have; in particular, normal code doesn't need to care about two kinds of references, etc. And we get to keep the optimization Nick's variant had bought us... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-01-13Merge branch 'for-linus' of ↵Linus Torvalds1-2/+2
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6: (41 commits) fs: add documentation on fallocate hole punching Gfs2: fail if we try to use hole punch Btrfs: fail if we try to use hole punch Ext4: fail if we try to use hole punch Ocfs2: handle hole punching via fallocate properly XFS: handle hole punching via fallocate properly fs: add hole punching to fallocate vfs: pass struct file to do_truncate on O_TRUNC opens (try #2) fix signedness mess in rw_verify_area() on 64bit architectures fs: fix kernel-doc for dcache::prepend_path fs: fix kernel-doc for dcache::d_validate sanitize ecryptfs ->mount() switch afs move internal-only parts of ncpfs headers to fs/ncpfs switch ncpfs switch 9p pass default dentry_operations to mount_pseudo() switch hostfs switch affs switch configfs ...
2011-01-13pipe: use event aware wakeupsDavide Libenzi1-5/+5
Send the events the wakeup refers to, so that epoll, and even the new poll code in fs/select.c can avoid wakeups if the events do not match the requested set. Signed-off-by: Davide Libenzi <davidel@xmailserver.org> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Eric Dumazet <eric.dumazet@gmail.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-01-12pass default dentry_operations to mount_pseudo()Al Viro1-2/+2
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-01-07fs: scale mntget/mntputNick Piggin1-1/+1
The problem that this patch aims to fix is vfsmount refcounting scalability. We need to take a reference on the vfsmount for every successful path lookup, which often go to the same mount point. The fundamental difficulty is that a "simple" reference count can never be made scalable, because any time a reference is dropped, we must check whether that was the last reference. To do that requires communication with all other CPUs that may have taken a reference count. We can make refcounts more scalable in a couple of ways, involving keeping distributed counters, and checking for the global-zero condition less frequently. - check the global sum once every interval (this will delay zero detection for some interval, so it's probably a showstopper for vfsmounts). - keep a local count and only taking the global sum when local reaches 0 (this is difficult for vfsmounts, because we can't hold preempt off for the life of a reference, so a counter would need to be per-thread or tied strongly to a particular CPU which requires more locking). - keep a local difference of increments and decrements, which allows us to sum the total difference and hence find the refcount when summing all CPUs. Then, keep a single integer "long" refcount for slow and long lasting references, and only take the global sum of local counters when the long refcount is 0. This last scheme is what I implemented here. Attached mounts and process root and working directory references are "long" references, and everything else is a short reference. This allows scalable vfsmount references during path walking over mounted subtrees and unattached (lazy umounted) mounts with processes still running in them. This results in one fewer atomic op in the fastpath: mntget is now just a per-CPU inc, rather than an atomic inc; and mntput just requires a spinlock and non-atomic decrement in the common case. However code is otherwise bigger and heavier, so single threaded performance is basically a wash. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: improve scalability of pseudo filesystemsNick Piggin1-1/+1
Regardless of how much we possibly try to scale dcache, there is likely always going to be some fundamental contention when adding or removing children under the same parent. Pseudo filesystems do not seem need to have connected dentries because by definition they are disconnected. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
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