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* nfsd: Push mnt_want_write() outside of i_mutexJan Kara2012-07-316-46/+64
| | | | | | | | | | | 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>
* btrfs: Push mnt_want_write() outside of i_mutexJan Kara2012-07-311-12/+11
| | | | | | | | | | | 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>
* fat: Push mnt_want_write() outside of i_mutexJan Kara2012-07-311-8/+7
| | | | | | | | | | 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>
* fs: Push mnt_want_write() outside of i_mutexJan Kara2012-07-311-21/+25
| | | | | | | | | | | | | | | | | | | | | | 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>
* mm: Make default vm_ops provide ->page_mkwrite handlerJan Kara2012-07-313-0/+21
| | | | | | | | | | | | | | Make default vm_ops provide ->page_mkwrite handler. Currently it only updates file's modification times and gets locked page but later it will also handle filesystem freezing. 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>
* mm: Update file times from fault path only if .page_mkwrite is not setJan Kara2012-07-311-7/+7
| | | | | | | | | | | | | | Filesystems wanting to properly support freezing need to have control when file_update_time() is called. After pushing file_update_time() to all relevant .page_mkwrite implementations we can just stop calling file_update_time() when filesystem implements .page_mkwrite. 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>
* sysfs: Push file_update_time() into bin_page_mkwrite()Jan Kara2012-07-311-0/+2
| | | | | | | 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>
* gfs2: Push file_update_time() into gfs2_page_mkwrite()Jan Kara2012-07-311-0/+3
| | | | | | | | 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>
* 9p: Push file_update_time() into v9fs_vm_page_mkwrite()Jan Kara2012-07-311-0/+3
| | | | | | | | | 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>
* ceph: Push file_update_time() into ceph_page_mkwrite()Jan Kara2012-07-311-0/+3
| | | | | | | | 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>
* fs: Push file_update_time() into __block_page_mkwrite()Jan Kara2012-07-311-0/+6
| | | | | | | | | 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>
* fb_defio: Push file_update_time() into fb_deferred_io_mkwrite()Jan Kara2012-07-311-0/+2
| | | | | | CC: Jaya Kumar <jayalk@intworks.biz> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* simplify lookup_open()/atomic_open() - do the temporary mnt_want_write() earlyAl Viro2012-07-311-22/+29
| | | | | | | | | | | | | | 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>
* fix O_EXCL handling for devicesAl Viro2012-07-301-2/+2
| | | | | | | 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>
* lockd: handle lockowner allocation failure in nlmclnt_proc()Al Viro2012-07-291-0/+5
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* lockd: shift grabbing a reference to nlm_host into nlm_alloc_call()Al Viro2012-07-294-8/+4
| | | | | | | | 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>
* fs: add link restriction audit reportingKees Cook2012-07-293-0/+27
| | | | | | | | | 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>
* fs: add link restrictionsKees Cook2012-07-294-0/+184
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* vfs: don't let do_last pass negative dentry to audit_inodeJeff Layton2012-07-291-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* brcm80211: pointless current->files passed to filp_close()Al Viro2012-07-291-1/+1
| | | | | | ... only needed if it's been in descriptor table Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* sound_firmware: don't pass crap to filp_close()Al Viro2012-07-291-4/+4
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* gadgetfs: clean upAl Viro2012-07-292-10/+8
| | | | | | | | | sigh... * opened files have non-NULL dentries and non-NULL inodes * close_filp() needs current->files only if the file had been in descriptor table. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* slightly reduce lossage in gdm72xxAl Viro2012-07-292-17/+12
| | | | | | | | | | * filp_close() needs non-NULL second argument only if it'd been in descriptor table * opened files have non-NULL dentries, TYVM * ... and those dentries are positive - it's kinda hard to open a file that doesn't exist. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* slightly reduce idiocy in drivers/staging/bcm/Misc.cAl Viro2012-07-291-26/+5
| | | | | | | | | | | | | | a) vfs_llseek() does *not* access userland pointers of any kind b) neither does filp_close(), for that matter c) ... nor filp_open() d) vfs_read() does, but we do have a wrapper for that (kernel_read()), so there's no need to reinvent it. e) passing current->files to filp_close() on something that never had been in descriptor table is pointless. ISAGN: voodoo dolls to be used on voodoo programmers... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* consolidate pipe file creationAl Viro2012-07-294-65/+34
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* take grabbing f->f_path to do_dentry_open()Al Viro2012-07-291-4/+2
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* uninline file_free_rcu()Al Viro2012-07-291-1/+1
| | | | | | 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>
* ecryptfs_lookup_interpose(): allocate dentry_info firstAl Viro2012-07-291-7/+6
| | | | | | less work on failure that way Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* sanitize ecryptfs_lookup()Al Viro2012-07-291-13/+4
| | | | | | | | | * ->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>
* clean unix_bind() up a bitAl Viro2012-07-291-45/+43
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* pull mnt_want_write()/mnt_drop_write() into ↵Al Viro2012-07-293-50/+18
| | | | | | | | | 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>
* mknod: take sanity checks on mode into the very beginningAl Viro2012-07-291-5/+3
| | | | | | | | | | | | | 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>
* new helper: done_path_create()Al Viro2012-07-296-30/+21
| | | | | | releases what needs to be released after {kern,user}_path_create() Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* pull unlock+dput() out into do_spu_create()Al Viro2012-07-292-16/+11
| | | | | | ... and cleaning spufs_create() a bit, while we are at it Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* spufs: pull unlock-and-dput() up into spufs_create()Al Viro2012-07-291-23/+10
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* spufs_create_context(): simplify failure exitsAl Viro2012-07-291-7/+1
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* move spu_forget() into spufs_rmdir()Al Viro2012-07-291-6/+5
| | | | | | | now that __fput() is *not* done in any callchain containing mmput(), we can do that... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* ext4: switch EXT4_IOC_RESIZE_FS to mnt_want_write_file()Al Viro2012-07-231-2/+2
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* btrfs: switch btrfs_ioctl_balance() to mnt_want_write_file()Al Viro2012-07-231-2/+2
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* switch dentry_open() to struct path, make it grab references itselfAl Viro2012-07-2315-151/+106
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* spufs: shift dget/mntget towards dentry_open()Al Viro2012-07-231-28/+18
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* zoran: don't bother with struct file * in zoran_mapAl Viro2012-07-232-3/+5
| | | | | | | | all we need it for is file->private_data, which is assign-once, already assigned by that point and, incidentally, its value is already in use by zoran ->mmap() anyway. So just store that pointer instead... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* ecryptfs: don't reinvent the wheels, please - use struct completionAl Viro2012-07-233-65/+26
| | | | | | ... and keep the sodding requests on stack - they are small enough. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* don't expose I_NEW inodes via dentry->d_inodeAl Viro2012-07-237-19/+19
| | | | | | | | | 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>
* tidy up namei.c a bitAl Viro2012-07-231-18/+21
| | | | | | locking/unlocking for rcu walk taken to a couple of inline helpers Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* unobfuscate follow_up() a bitAl Viro2012-07-231-1/+1
| | | | | | 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.
* ext3: pass custom EOF to generic_file_llseek_size()Eric Sandeen2012-07-231-2/+2
| | | | | | | | | 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>
* ext4: use core vfs llseek code for dir seeksEric Sandeen2012-07-232-64/+17
| | | | | | | | | | | 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>
* vfs: allow custom EOF in generic_file_llseek codeEric Sandeen2012-07-234-11/+15
| | | | | | | | | | | | | | | | | | | | | | | | 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>
* vfs: Avoid unnecessary WB_SYNC_NONE writeback during sys_sync and reorder ↵Jan Kara2012-07-221-10/+9
| | | | | | | | | | | | | | | | | | 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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