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* sysrq: Emergency Remount R/O in reverse orderAmir Goldstein2018-12-021-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This change fixes a problem where reboot on Android panics the kernel almost every time when file systems are mounted over loop devices. Android reboot command does: - sync - echo u > /proc/sysrq-trigger - syscall_reboot The problem is with sysrq emergency remount R/O trying to remount-ro in wrong order. since /data is re-mounted ro before loop devices, loop device remount-ro fails to flush the journal and panics the kernel: EXT4-fs (loop0): Remounting filesystem read-only EXT4-fs (loop0): previous I/O error to superblock detected loop: Write error at byte offset 0, length 4096. Buffer I/O error on device loop0, logical block 0 lost page write due to I/O error on loop0 Kernel panic - not syncing: EXT4-fs panic from previous error The fix is quite simple. In do_emergency_remount(), use list_for_each_entry_reverse() on sb list instead of list_for_each_entry(). It makes a lot of sense to umount the file systems in reverse order in which they were added to sb list. Change-Id: I4370e39b5873bd16ade5d5f9ddb2704beb02a2bb Signed-off-by: Amir Goldstein <amir@cellrox.com> Acked-by: Oren Laadan <orenl@cellrox.com>
* non-ext4 portions of "direct-io: Implement generic deferred AIO completions"Theodore Ts'o2017-05-271-9/+9
| | | | | | Originally from 7b7a8665edd8db73 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
* vfs: Allow filesystems to access their private mount dataDaniel Rosenberg2017-04-131-5/+23
| | | | | | | | | | | | | | Now we pass the vfsmount when mounting and remounting. This allows the filesystem to actually set up the mount specific data, although we can't quite do anything with it yet. show_options is expanded to include data that lives with the mount. To avoid changing existing filesystems, these have been added as new vfs functions. Change-Id: If80670bfad9f287abb8ac22457e1b034c9697097 Signed-off-by: Daniel Rosenberg <drosen@google.com>
* fs/super.c: fix race between freeze_super() and thaw_super()Oleg Nesterov2017-04-111-3/+3
| | | | | | | | | | | | | | | | | | commit 89f39af129382a40d7cd1f6914617282cfeee28e upstream. Change thaw_super() to check frozen != SB_FREEZE_COMPLETE rather than frozen == SB_UNFROZEN, otherwise it can race with freeze_super() which drops sb->s_umount after SB_FREEZE_WRITE to preserve the lock ordering. In this case thaw_super() will wrongly call s_op->unfreeze_fs() before it was actually frozen, and call sb_freeze_unlock() which leads to the unbalanced percpu_up_write(). Unfortunately lockdep can't detect this, so this triggers misc BUG_ON()'s in kernel/rcu/sync.c. Reported-and-tested-by: Nikolay Borisov <kernel@kyup.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Willy Tarreau <w@1wt.eu>
* get rid of s_files and files_lockAl Viro2016-08-261-21/+2
| | | | | | | | | | | | | | commit eee5cc2702929fd41cce28058dc6d6717f723f87 upstream. The only thing we need it for is alt-sysrq-r (emergency remount r/o) and these days we can do just as well without going through the list of files. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> [wangkai: backport to 3.10: adjust context] Signed-off-by: Wang Kai <morgan.wang@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Stefan Guendhoer <stefan@guendhoer.com>
* first commitMeizu OpenSource2016-08-151-0/+1401