| Age | Commit message (Collapse) | Author |
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We remove most of frozen checks since upper layer takes care of blocking all
writes. We have to handle protection in ext4_page_mkwrite() in a special way
because we cannot use generic block_page_mkwrite(). Also we add a freeze
protection to ext4_evict_inode() so that iput() of unlinked inode cannot modify
a frozen filesystem (we cannot easily instrument ext4_journal_start() /
ext4_journal_stop() with freeze protection because we are missing the
superblock pointer in ext4_journal_stop() in nojournal mode).
CC: linux-ext4@vger.kernel.org
CC: "Theodore Ts'o" <tytso@mit.edu>
BugLink: https://bugs.launchpad.net/bugs/897421
Tested-by: Kamal Mostafa <kamal@canonical.com>
Tested-by: Peter M. Petrakis <peter.petrakis@canonical.com>
Tested-by: Dann Frazier <dann.frazier@canonical.com>
Tested-by: Massimo Morana <massimo.morana@canonical.com>
Acked-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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There are several entry points which dirty pages in a filesystem. mmap
(handled by block_page_mkwrite()), buffered write (handled by
__generic_file_aio_write()), splice write (generic_file_splice_write),
truncate, and fallocate (these can dirty last partial page - handled inside
each filesystem separately). Protect these places with sb_start_write() and
sb_end_write().
->page_mkwrite() calls are particularly complex since they are called with
mmap_sem held and thus we cannot use standard sb_start_write() due to lock
ordering constraints. We solve the problem by using a special freeze protection
sb_start_pagefault() which ranks below mmap_sem.
BugLink: https://bugs.launchpad.net/bugs/897421
Tested-by: Kamal Mostafa <kamal@canonical.com>
Tested-by: Peter M. Petrakis <peter.petrakis@canonical.com>
Tested-by: Dann Frazier <dann.frazier@canonical.com>
Tested-by: Massimo Morana <massimo.morana@canonical.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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It is unexpected to block reading of frozen filesystem because of atime update.
Also handling blocking on frozen filesystem because of atime update would make
locking more complex than it already is. So just skip atime update when
filesystem is frozen like we skip it when filesystem is remounted read-only.
BugLink: https://bugs.launchpad.net/bugs/897421
Tested-by: Kamal Mostafa <kamal@canonical.com>
Tested-by: Peter M. Petrakis <peter.petrakis@canonical.com>
Tested-by: Dann Frazier <dann.frazier@canonical.com>
Tested-by: Massimo Morana <massimo.morana@canonical.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Most of places where we want freeze protection coincides with the places where
we also have remount-ro protection. So make mnt_want_write() and
mnt_drop_write() (and their _file alternative) prevent freezing as well.
For the few cases that are really interested only in remount-ro protection
provide new function variants.
BugLink: https://bugs.launchpad.net/bugs/897421
Tested-by: Kamal Mostafa <kamal@canonical.com>
Tested-by: Peter M. Petrakis <peter.petrakis@canonical.com>
Tested-by: Dann Frazier <dann.frazier@canonical.com>
Tested-by: Massimo Morana <massimo.morana@canonical.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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vfs_check_frozen() tests are racy since the filesystem can be frozen just after
the test is performed. Thus in write paths we can end up marking some pages or
inodes dirty even though the file system is already frozen. This creates
problems with flusher thread hanging on frozen filesystem.
Another problem is that exclusion between ->page_mkwrite() and filesystem
freezing has been handled by setting page dirty and then verifying s_frozen.
This guaranteed that either the freezing code sees the faulted page, writes it,
and writeprotects it again or we see s_frozen set and bail out of page fault.
This works to protect from page being marked writeable while filesystem
freezing is running but has an unpleasant artefact of leaving dirty (although
unmodified and writeprotected) pages on frozen filesystem resulting in similar
problems with flusher thread as the first problem.
This patch aims at providing exclusion between write paths and filesystem
freezing. We implement a writer-freeze read-write semaphore in the superblock.
Actually, there are three such semaphores because of lock ranking reasons - one
for page fault handlers (->page_mkwrite), one for all other writers, and one of
internal filesystem purposes (used e.g. to track running transactions). Write
paths which should block freezing (e.g. directory operations, ->aio_write(),
->page_mkwrite) hold reader side of the semaphore. Code freezing the filesystem
takes the writer side.
Only that we don't really want to bounce cachelines of the semaphores between
CPUs for each write happening. So we implement the reader side of the semaphore
as a per-cpu counter and the writer side is implemented using s_writers.frozen
superblock field.
[AV: microoptimize sb_start_write(); we want it fast in normal case]
BugLink: https://bugs.launchpad.net/bugs/897421
Tested-by: Kamal Mostafa <kamal@canonical.com>
Tested-by: Peter M. Petrakis <peter.petrakis@canonical.com>
Tested-by: Dann Frazier <dann.frazier@canonical.com>
Tested-by: Massimo Morana <massimo.morana@canonical.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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When mnt_want_write() starts to handle freezing it will get a full lock
semantics requiring proper lock ordering. So push mnt_want_write() call
consistently outside of i_mutex.
CC: linux-nfs@vger.kernel.org
CC: "J. Bruce Fields" <bfields@fieldses.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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When mnt_want_write() starts to handle freezing it will get a full lock
semantics requiring proper lock ordering. So push mnt_want_write() call
consistently outside of i_mutex.
CC: Chris Mason <chris.mason@oracle.com>
CC: linux-btrfs@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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When mnt_want_write() starts to handle freezing it will get a full lock
semantics requiring proper lock ordering. So push mnt_want_write() call
outside of i_mutex as in other places.
CC: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Currently, mnt_want_write() is sometimes called with i_mutex held and sometimes
without it. This isn't really a problem because mnt_want_write() is a
non-blocking operation (essentially has a trylock semantics) but when the
function starts to handle also frozen filesystems, it will get a full lock
semantics and thus proper lock ordering has to be established. So move
all mnt_want_write() calls outside of i_mutex.
One non-trivial case needing conversion is kern_path_create() /
user_path_create() which didn't include mnt_want_write() but now needs to
because it acquires i_mutex. Because there are virtual file systems which
don't bother with freeze / remount-ro protection we actually provide both
versions of the function - one which calls mnt_want_write() and one which does
not.
[AV: scratch the previous, mnt_want_write() has been moved to kern_path_create()
by now]
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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CC: Steven Whitehouse <swhiteho@redhat.com>
CC: cluster-devel@redhat.com
Acked-by: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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CC: Eric Van Hensbergen <ericvh@gmail.com>
CC: Ron Minnich <rminnich@sandia.gov>
CC: Latchesar Ionkov <lucho@ionkov.net>
CC: v9fs-developer@lists.sourceforge.net
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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CC: Sage Weil <sage@newdream.net>
CC: ceph-devel@vger.kernel.org
Acked-by: Sage Weil <sage@newdream.net>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Tested-by: Kamal Mostafa <kamal@canonical.com>
Tested-by: Peter M. Petrakis <peter.petrakis@canonical.com>
Tested-by: Dann Frazier <dann.frazier@canonical.com>
Tested-by: Massimo Morana <massimo.morana@canonical.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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The write ref to vfsmount taken in lookup_open()/atomic_open() is going to
be dropped; we take the one to stay in dentry_open(). Just grab the temporary
in caller if it looks like we are going to need it (create/truncate/writable open)
and pass (by value) "has it succeeded" flag. Instead of doing mnt_want_write()
inside, check that flag and treat "false" as "mnt_want_write() has just failed".
mnt_want_write() is cheap and the things get considerably simpler and more robust
that way - we get it and drop it in the same function, to start with, rather
than passing a "has something in the guts of really scary functions taken it"
back to caller.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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O_EXCL without O_CREAT has different semantics; it's "fail if already opened",
not "fail if already exists". commit 71574865 broke that...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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It's used both for client and server hosts; we can't do nlmclnt_release_host()
on failure exits, since the host might need nlmsvc_release_host(), with BUG_ON()
for calling the wrong one. Makes life simpler for callers, actually...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Adds audit messages for unexpected link restriction violations so that
system owners will have some sort of potentially actionable information
about misbehaving processes.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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This adds symlink and hardlink restrictions to the Linux VFS.
Symlinks:
A long-standing class of security issues is the symlink-based
time-of-check-time-of-use race, most commonly seen in world-writable
directories like /tmp. The common method of exploitation of this flaw
is to cross privilege boundaries when following a given symlink (i.e. a
root process follows a symlink belonging to another user). For a likely
incomplete list of hundreds of examples across the years, please see:
http://cve.mitre.org/cgi-bin/cvekey.cgi?keyword=/tmp
The solution is to permit symlinks to only be followed when outside
a sticky world-writable directory, or when the uid of the symlink and
follower match, or when the directory owner matches the symlink's owner.
Some pointers to the history of earlier discussion that I could find:
1996 Aug, Zygo Blaxell
http://marc.info/?l=bugtraq&m=87602167419830&w=2
1996 Oct, Andrew Tridgell
http://lkml.indiana.edu/hypermail/linux/kernel/9610.2/0086.html
1997 Dec, Albert D Cahalan
http://lkml.org/lkml/1997/12/16/4
2005 Feb, Lorenzo Hernández García-Hierro
http://lkml.indiana.edu/hypermail/linux/kernel/0502.0/1896.html
2010 May, Kees Cook
https://lkml.org/lkml/2010/5/30/144
Past objections and rebuttals could be summarized as:
- Violates POSIX.
- POSIX didn't consider this situation and it's not useful to follow
a broken specification at the cost of security.
- Might break unknown applications that use this feature.
- Applications that break because of the change are easy to spot and
fix. Applications that are vulnerable to symlink ToCToU by not having
the change aren't. Additionally, no applications have yet been found
that rely on this behavior.
- Applications should just use mkstemp() or O_CREATE|O_EXCL.
- True, but applications are not perfect, and new software is written
all the time that makes these mistakes; blocking this flaw at the
kernel is a single solution to the entire class of vulnerability.
- This should live in the core VFS.
- This should live in an LSM. (https://lkml.org/lkml/2010/5/31/135)
- This should live in an LSM.
- This should live in the core VFS. (https://lkml.org/lkml/2010/8/2/188)
Hardlinks:
On systems that have user-writable directories on the same partition
as system files, a long-standing class of security issues is the
hardlink-based time-of-check-time-of-use race, most commonly seen in
world-writable directories like /tmp. The common method of exploitation
of this flaw is to cross privilege boundaries when following a given
hardlink (i.e. a root process follows a hardlink created by another
user). Additionally, an issue exists where users can "pin" a potentially
vulnerable setuid/setgid file so that an administrator will not actually
upgrade a system fully.
The solution is to permit hardlinks to only be created when the user is
already the existing file's owner, or if they already have read/write
access to the existing file.
Many Linux users are surprised when they learn they can link to files
they have no access to, so this change appears to follow the doctrine
of "least surprise". Additionally, this change does not violate POSIX,
which states "the implementation may require that the calling process
has permission to access the existing file"[1].
This change is known to break some implementations of the "at" daemon,
though the version used by Fedora and Ubuntu has been fixed[2] for
a while. Otherwise, the change has been undisruptive while in use in
Ubuntu for the last 1.5 years.
[1] http://pubs.opengroup.org/onlinepubs/9699919799/functions/linkat.html
[2] http://anonscm.debian.org/gitweb/?p=collab-maint/at.git;a=commitdiff;h=f4114656c3a6c6f6070e315ffdf940a49eda3279
This patch is based on the patches in Openwall and grsecurity, along with
suggestions from Al Viro. I have added a sysctl to enable the protected
behavior, and documentation.
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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I can reliably reproduce the following panic by simply setting an audit
rule on a recent 3.5.0+ kernel:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000040
IP: [<ffffffff810d1250>] audit_copy_inode+0x10/0x90
PGD 7acd9067 PUD 7b8fb067 PMD 0
Oops: 0000 [#86] SMP
Modules linked in: nfs nfs_acl auth_rpcgss fscache lockd sunrpc tpm_bios btrfs zlib_deflate libcrc32c kvm_amd kvm joydev virtio_net pcspkr i2c_piix4 floppy virtio_balloon microcode virtio_blk cirrus drm_kms_helper ttm drm i2c_core [last unloaded: scsi_wait_scan]
CPU 0
Pid: 1286, comm: abrt-dump-oops Tainted: G D 3.5.0+ #1 Bochs Bochs
RIP: 0010:[<ffffffff810d1250>] [<ffffffff810d1250>] audit_copy_inode+0x10/0x90
RSP: 0018:ffff88007aebfc38 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffff88003692d860 RCX: 00000000000038c4
RDX: 0000000000000000 RSI: ffff88006baf5d80 RDI: ffff88003692d860
RBP: ffff88007aebfc68 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000000
R13: ffff880036d30f00 R14: ffff88006baf5d80 R15: ffff88003692d800
FS: 00007f7562634740(0000) GS:ffff88007fc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000040 CR3: 000000003643d000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process abrt-dump-oops (pid: 1286, threadinfo ffff88007aebe000, task ffff880079614530)
Stack:
ffff88007aebfdf8 ffff88007aebff28 ffff88007aebfc98 ffffffff81211358
ffff88003692d860 0000000000000000 ffff88007aebfcc8 ffffffff810d4968
ffff88007aebfcc8 ffff8800000038c4 0000000000000000 0000000000000000
Call Trace:
[<ffffffff81211358>] ? ext4_lookup+0xe8/0x160
[<ffffffff810d4968>] __audit_inode+0x118/0x2d0
[<ffffffff811955a9>] do_last+0x999/0xe80
[<ffffffff81191fe8>] ? inode_permission+0x18/0x50
[<ffffffff81171efa>] ? kmem_cache_alloc_trace+0x11a/0x130
[<ffffffff81195b4a>] path_openat+0xba/0x420
[<ffffffff81196111>] do_filp_open+0x41/0xa0
[<ffffffff811a24bd>] ? alloc_fd+0x4d/0x120
[<ffffffff811855cd>] do_sys_open+0xed/0x1c0
[<ffffffff810d40cc>] ? __audit_syscall_entry+0xcc/0x300
[<ffffffff811856c1>] sys_open+0x21/0x30
[<ffffffff81611ca9>] system_call_fastpath+0x16/0x1b
RSP <ffff88007aebfc38>
CR2: 0000000000000040
The problem is that do_last is passing a negative dentry to audit_inode.
The comments on lookup_open note that it can pass back a negative dentry
if O_CREAT is not set.
This patch fixes the oops, but I'm not clear on whether there's a better
approach.
Cc: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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What inline? Its only use is passing its address to call_rcu(), for fuck sake!
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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less work on failure that way
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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* ->lookup() never gets hit with . or ..
* dentry it gets is unhashed, so unless we had gone and hashed it ourselves, there's
no need to d_drop() the sucker.
* wrong name printed in one of the printks (NULL, in fact)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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kern_path_create()/done_path_create() resp.
One side effect - attempt to create a cross-device link on a read-only fs fails
with EROFS instead of EXDEV now. Makes more sense, POSIX allows, etc.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Note that applying umask can't affect their results. While
that affects errno in cases like
mknod("/no_such_directory/a", 030000)
yielding -EINVAL (due to impossible mode_t) instead of
-ENOENT (due to inexistent directory), IMO that makes a lot
more sense, POSIX allows to return either and any software
that relies on getting -ENOENT instead of -EINVAL in that
case deserves everything it gets.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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releases what needs to be released after {kern,user}_path_create()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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... and keep the sodding requests on stack - they are small enough.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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d_instantiate(dentry, inode);
unlock_new_inode(inode);
is a bad idea; do it the other way round...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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locking/unlocking for rcu walk taken to a couple of inline helpers
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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really convoluted test in there has grown up during struct mount
introduction; what it checks is that we'd reached the root of
mount tree.
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Use the new custom EOF argument to generic_file_llseek_size so
that SEEK_END will go to the max hash value for htree dirs
in ext3 rather than to i_size_read()
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Use the new functionality in generic_file_llseek_size() to
accept a custom EOF position, and un-cut-and-paste all the
vfs llseek code from ext4.
Also fix up comments on ext4_llseek() to reflect reality.
Signed-off-by: Eric Sandeen <sandeen@redaht.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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For ext3/4 htree directories, using the vfs llseek function with
SEEK_END goes to i_size like for any other file, but in reality
we want the maximum possible hash value. Recent changes
in ext4 have cut & pasted generic_file_llseek() back into fs/ext4/dir.c,
but replicating this core code seems like a bad idea, especially
since the copy has already diverged from the vfs.
This patch updates generic_file_llseek_size to accept
both a custom maximum offset, and a custom EOF position. With this
in place, ext4_dir_llseek can pass in the appropriate maximum hash
position for both maxsize and eof, and get what it wants.
As far as I know, this does not fix any bugs - nfs in the kernel
doesn't use SEEK_END, and I don't know of any user who does. But
some ext4 folks seem keen on doing the right thing here, and I can't
really argue.
(Patch also fixes up some comments slightly)
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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sync passes
wakeup_flusher_threads(0) will queue work doing complete writeback for each
flusher thread. Thus there is not much point in submitting another work doing
full inode WB_SYNC_NONE writeback by writeback_inodes_sb().
After this change it does not make sense to call nonblocking ->sync_fs and
block device flush before calling sync_inodes_sb() because
wakeup_flusher_threads() is completely asynchronous and thus these functions
would be called in parallel with inode writeback running which will effectively
void any work they do. So we move sync_inodes_sb() call before these two
functions.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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It is not necessary to write block devices twice. The reason why we first did
flush and then proper sync is that
for_each_bdev() {
write_bdev()
wait_for_completion()
}
is much slower than
for_each_bdev()
write_bdev()
for_each_bdev()
wait_for_completion()
when there is bigger amount of data. But as is seen in the above, there's no real
need to scan pages and submit them twice. We just need to separate the submission
and waiting part. This patch does that.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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In case block device does not have filesystem mounted on it, sys_sync will just
ignore it and doesn't writeout its dirty pages. This is because writeback code
avoids writing inodes from superblock without backing device and
blockdev_superblock is such a superblock. Since it's unexpected that sync
doesn't writeout dirty data for block devices be nice to users and change the
behavior to do so. So now we iterate over all block devices on blockdev_super
instead of iterating over all superblocks when syncing block devices.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Change the order of operations during sync from
for_each_sb {
writeback_inodes_sb();
sync_fs(nowait);
__sync_blockdev(nowait);
}
for_each_sb {
sync_inodes_sb();
sync_fs(wait);
__sync_blockdev(wait);
}
to
for_each_sb
writeback_inodes_sb();
for_each_sb
sync_fs(nowait);
for_each_sb
__sync_blockdev(nowait);
for_each_sb
sync_inodes_sb();
for_each_sb
sync_fs(wait);
for_each_sb
__sync_blockdev(wait);
This is a preparation for the following patches in this series.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Since the moment writes to quota files are using block device page cache and
space for quota structures is reserved at the moment they are first accessed we
have no reason to sync quota before inode writeback. In fact this order is now
only harmful since quota information can easily change during inode writeback
(either because conversion of delayed-allocated extents or simply because of
allocation of new blocks for simple filesystems not using page_mkwrite).
So move syncing of quota information after writeback of inodes into ->sync_fs
method. This way we do not have to use ->quota_sync callback which is primarily
intended for use by quotactl syscall anyway and we get rid of calling
->sync_fs() twice unnecessarily. We skip quota syncing for OCFS2 since it does
proper quota journalling in all cases (unlike ext3, ext4, and reiserfs which
also support legacy non-journalled quotas) and thus there are no dirty quota
structures.
CC: "Theodore Ts'o" <tytso@mit.edu>
CC: Joel Becker <jlbec@evilplan.org>
CC: reiserfs-devel@vger.kernel.org
Acked-by: Steven Whitehouse <swhiteho@redhat.com>
Acked-by: Dave Kleikamp <shaggy@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Split off part of dquot_quota_sync() which writes dquots into a quota file
to a separate function. In the next patch we will use the function from
filesystems and we do not want to abuse ->quota_sync quotactl callback more
than necessary.
Acked-by: Steven Whitehouse <swhiteho@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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In principle, a filesystem may want to have ->sync_fs() called during sync(1)
although it does not have a bdi (i.e. s_bdi is set to noop_backing_dev_info).
Only writeback code really needs bdi set to something reasonable. So move the
checks where they are more logical.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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This patch makes UFS stop using the VFS '->write_super()' method along with
the 's_dirt' superblock flag, because they are on their way out.
The way we implement this is that we schedule a delay job instead relying on
's_dirt' and '->write_super()'.
The whole "superblock write-out" VFS infrastructure is served by the
'sync_supers()' kernel thread, which wakes up every 5 (by default) seconds and
writes out all dirty superblocks using the '->write_super()' call-back. But the
problem with this thread is that it wastes power by waking up the system every
5 seconds, even if there are no diry superblocks, or there are no client
file-systems which would need this (e.g., btrfs does not use
'->write_super()'). So we want to kill it completely and thus, we need to make
file-systems to stop using the '->write_super()' VFS service, and then remove
it together with the kernel thread.
Tested using fsstress from the LTP project.
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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This patch does not do any functional changes. It only moves 3 functions
in fs/ufs/super.c a little bit up in order to prepare for further changes
where I'll need this new arrangement to avoid forward declarations.
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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UFS calls 'ufs_write_super()' from 'ufs_put_super()' in order to write the
superblocks to the media. However, it is not needed because VFS calls
'->sync_fs()' before calling '->put_super()' - so by the time we are in
'ufs_write_super()', the superblocks are already synchronized.
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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