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4ed5e82fe7
linux/fs
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Miklos Szeredi 4ed5e82fe7 vfs: protect remounting superblock read-only 
Currently remouting superblock read-only is racy in a major way.

With the per mount read-only infrastructure it is now possible to
prevent most races, which this patch attempts.

Before starting the remount read-only, iterate through all mounts
belonging to the superblock and if none of them have any pending
writes, set sb->s_readonly_remount.  This indicates that remount is in
progress and no further write requests are allowed.  If the remount
succeeds set MS_RDONLY and reset s_readonly_remount.

If the remounting is unsuccessful just reset s_readonly_remount.
This can result in transient EROFS errors, despite the fact the
remount failed.  Unfortunately hodling off writes is difficult as
remount itself may touch the filesystem (e.g. through load_nls())
which would deadlock.

A later patch deals with delayed writes due to nlink going to zero.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Tested-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-06 23:20:12 -05:00
..
9p 9p: propagate umode_t 2012-01-03 22:55:01 -05:00
adfs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
affs affs: propagate umode_t 2012-01-03 22:55:04 -05:00
afs switch ->create() to umode_t 2012-01-03 22:54:53 -05:00
autofs4 vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
befs vfs: fix the stupidity with i_dentry in inode destructors 2012-01-03 22:52:40 -05:00
bfs switch ->create() to umode_t 2012-01-03 22:54:53 -05:00
btrfs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
cachefiles fs: move code out of buffer.c 2012-01-03 22:54:07 -05:00
ceph vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
cifs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
coda switch ->create() to umode_t 2012-01-03 22:54:53 -05:00
configfs configfs: convert to umode_t 2012-01-03 22:54:57 -05:00
cramfs Merge branches 'vfsmount-guts', 'umode_t' and 'partitions' into Z 2012-01-06 23:15:54 -05:00
debugfs switch debugfs to umode_t 2012-01-03 22:54:56 -05:00
devpts vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
dlm
ecryptfs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
efs vfs: fix the stupidity with i_dentry in inode destructors 2012-01-03 22:52:40 -05:00
exofs exofs: propagate umode_t 2012-01-03 22:55:05 -05:00
exportfs
ext2 vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
ext3 vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
ext4 vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
fat vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
freevxfs fs: propagate umode_t, misc bits 2012-01-03 22:55:10 -05:00
fscache
fuse vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
gfs2 vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
hfs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
hfsplus vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
hostfs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
hpfs switch ->mknod() to umode_t 2012-01-03 22:54:54 -05:00
hppfs vfs: for usbfs, etc. internal vfsmounts ->mnt_sb->s_root == ->mnt_root 2012-01-03 22:52:41 -05:00
hugetlbfs hugetlbfs: propagate umode_t 2012-01-03 22:55:05 -05:00
isofs isofs: propagate umode_t 2012-01-03 22:55:08 -05:00
jbd jbd/jbd2: validate sb->s_first in journal_get_superblock() 2011-11-01 19:04:59 -04:00
jbd2 jbd2: Unify log messages in jbd2 code 2011-11-01 19:09:18 -04:00
jffs2 vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
jfs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
lockd vfs: prefer ->dentry->d_sb to ->mnt->mnt_sb 2012-01-06 23:16:53 -05:00
logfs logfs: propagate umode_t 2012-01-03 22:55:06 -05:00
minix minix: propagate umode_t 2012-01-03 22:54:59 -05:00
ncpfs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
nfs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
nfs_common
nfsd vfs: prefer ->dentry->d_sb to ->mnt->mnt_sb 2012-01-06 23:16:53 -05:00
nilfs2 vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
nls
notify vfs: move fsnotify junk to struct mount 2012-01-03 22:57:12 -05:00
ntfs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
ocfs2 vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
omfs omfs: propagate umode_t 2012-01-03 22:55:01 -05:00
openpromfs vfs: fix the stupidity with i_dentry in inode destructors 2012-01-03 22:52:40 -05:00
proc Merge branches 'vfsmount-guts', 'umode_t' and 'partitions' into Z 2012-01-06 23:15:54 -05:00
pstore pstore: pass allocated memory region back to caller 2011-11-17 12:58:07 -08:00
qnx4 vfs: fix the stupidity with i_dentry in inode destructors 2012-01-03 22:52:40 -05:00
quota vfs: prefer ->dentry->d_sb to ->mnt->mnt_sb 2012-01-06 23:16:53 -05:00
ramfs pohmelfs: propagate umode_t 2012-01-03 22:55:07 -05:00
reiserfs vfs: prefer ->dentry->d_sb to ->mnt->mnt_sb 2012-01-06 23:16:53 -05:00
romfs vfs: fix the stupidity with i_dentry in inode destructors 2012-01-03 22:52:40 -05:00
squashfs vfs: fix the stupidity with i_dentry in inode destructors 2012-01-03 22:52:40 -05:00
sysfs sysfs: propagate umode_t 2012-01-03 22:55:03 -05:00
sysv vfs: prefer ->dentry->d_sb to ->mnt->mnt_sb 2012-01-06 23:16:53 -05:00
ubifs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
udf vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
ufs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
xfs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
aio.c aio: allocate kiocbs in batches 2011-11-02 16:07:03 -07:00
anon_inodes.c
attr.c switch is_sxid() to umode_t 2012-01-03 22:55:11 -05:00
bad_inode.c switch ->mknod() to umode_t 2012-01-03 22:54:54 -05:00
binfmt_aout.c
binfmt_elf_fdpic.c
binfmt_elf.c binfmt_elf: fix PIE execution with randomization disabled 2011-11-02 16:06:58 -07:00
binfmt_em86.c
binfmt_flat.c
binfmt_misc.c vfs: prefer ->dentry->d_sb to ->mnt->mnt_sb 2012-01-06 23:16:53 -05:00
binfmt_script.c
binfmt_som.c
bio-integrity.c fs: add export.h to files using EXPORT_SYMBOL/THIS_MODULE macros 2011-10-31 19:30:31 -04:00
bio.c bio: change some signed vars to unsigned 2011-11-16 09:21:50 +01:00
block_dev.c fs: move code out of buffer.c 2012-01-03 22:54:07 -05:00
buffer.c fs: move code out of buffer.c 2012-01-03 22:54:07 -05:00
char_dev.c
compat_binfmt_elf.c
compat_ioctl.c
compat.c switch open and mkdir syscalls to umode_t 2012-01-03 22:55:19 -05:00
dcache.c vfs: mnt_ns moved to struct mount 2012-01-03 22:57:09 -05:00
dcookies.c
direct-io.c direct-io: merge direct_io_walker into __blockdev_direct_IO 2011-10-28 14:58:58 +02:00
drop_caches.c
eventfd.c
eventpoll.c epoll: fix spurious lockdep warnings 2011-10-31 17:30:57 -07:00
exec.c trim fs/internal.h 2012-01-03 22:52:35 -05:00
fcntl.c
fhandle.c vfs: prefer ->dentry->d_sb to ->mnt->mnt_sb 2012-01-06 23:16:53 -05:00
fifo.c
file_table.c
file.c
filesystems.c vfs: convert fs_supers to hlist 2012-01-03 22:52:39 -05:00
fs_struct.c
fs-writeback.c fs: move code out of buffer.c 2012-01-03 22:54:07 -05:00
generic_acl.c
inode.c switch inode_init_owner() to umode_t 2012-01-03 22:55:11 -05:00
internal.h vfs: protect remounting superblock read-only 2012-01-06 23:20:12 -05:00
ioctl.c
ioprio.c fs: add export.h to files using EXPORT_SYMBOL/THIS_MODULE macros 2011-10-31 19:30:31 -04:00
Kconfig move fs/partitions to block/ 2012-01-03 22:54:06 -05:00
Kconfig.binfmt
libfs.c fs: move code out of buffer.c 2012-01-03 22:54:07 -05:00
locks.c vfs: fix handling of lock allocation failure in lease-break case 2011-12-26 10:25:26 -08:00
Makefile Merge branches 'vfsmount-guts', 'umode_t' and 'partitions' into Z 2012-01-06 23:15:54 -05:00
mbcache.c
mount.h vfs: keep list of mounts for each superblock 2012-01-06 23:20:12 -05:00
mpage.c
namei.c Merge branches 'vfsmount-guts', 'umode_t' and 'partitions' into Z 2012-01-06 23:15:54 -05:00
namespace.c vfs: protect remounting superblock read-only 2012-01-06 23:20:12 -05:00
no-block.c
open.c switch security_path_chmod() to struct path * 2012-01-06 23:16:53 -05:00
pipe.c vfs: pipe.c is really non-modular 2012-01-03 22:52:41 -05:00
pnode.c vfs: switch pnode.h macros to struct mount * 2012-01-03 22:57:11 -05:00
pnode.h vfs: switch pnode.h macros to struct mount * 2012-01-03 22:57:11 -05:00
posix_acl.c vfs: pass all mask flags check_acl and posix_acl_permission 2011-10-28 14:58:54 +02:00
proc_namespace.c vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
read_write.c Cross Memory Attach 2011-10-31 17:30:44 -07:00
read_write.h
readdir.c
select.c
seq_file.c constify seq_file stuff 2012-01-03 22:52:40 -05:00
signalfd.c
splice.c fs: move code out of buffer.c 2012-01-03 22:54:07 -05:00
stack.c filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
stat.c readlinkat: ensure we return ENOENT for the empty pathname for normal lookups 2011-11-02 12:53:42 +01:00
statfs.c vfs: new helper - vfs_ustat() 2012-01-03 22:53:07 -05:00
super.c vfs: protect remounting superblock read-only 2012-01-06 23:20:12 -05:00
sync.c fs: move code out of buffer.c 2012-01-03 22:54:07 -05:00
timerfd.c
utimes.c
xattr_acl.c
xattr.c vfs: mnt_drop_write_file() 2012-01-03 22:52:40 -05:00