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authorDavid Howells <dhowells@redhat.com>2018-11-04 17:28:36 +0300
committerAl Viro <viro@zeniv.linux.org.uk>2019-01-31 01:44:26 +0300
commit8d0347f6c3a9d4953ddd636a31c6584da082e084 (patch)
treea8dec0e9d854bad8732ae41084e6f7c980713758 /fs/namespace.c
parentc9ce29ed795fae86e594844857fad1b0d3be85f4 (diff)
downloadlinux-8d0347f6c3a9d4953ddd636a31c6584da082e084.tar.xz
convert do_remount_sb() to fs_context
Replace do_remount_sb() with a function, reconfigure_super(), that's fs_context aware. The fs_context is expected to be parameterised already and have ->root pointing to the superblock to be reconfigured. A legacy wrapper is provided that is intended to be called from the fs_context ops when those appear, but for now is called directly from reconfigure_super(). This wrapper invokes the ->remount_fs() superblock op for the moment. It is intended that the remount_fs() op will be phased out. The fs_context->purpose is set to FS_CONTEXT_FOR_RECONFIGURE to indicate that the context is being used for reconfiguration. do_umount_root() is provided to consolidate remount-to-R/O for umount and emergency remount by creating a context and invoking reconfiguration. do_remount(), do_umount() and do_emergency_remount_callback() are switched to use the new process. [AV -- fold UMOUNT and EMERGENCY_REMOUNT in; fixes the umount / bug, gets rid of pointless complexity] [AV -- set ->net_ns in all cases; nfs remount will need that] [AV -- shift security_sb_remount() call into reconfigure_super(); the callers that didn't do security_sb_remount() have NULL fc->security anyway, so it's a no-op for them] Signed-off-by: David Howells <dhowells@redhat.com> Co-developed-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/namespace.c')
-rw-r--r--fs/namespace.c61
1 files changed, 39 insertions, 22 deletions
diff --git a/fs/namespace.c b/fs/namespace.c
index 750500c6c33d..931228d8518a 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1489,6 +1489,29 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
static void shrink_submounts(struct mount *mnt);
+static int do_umount_root(struct super_block *sb)
+{
+ int ret = 0;
+
+ down_write(&sb->s_umount);
+ if (!sb_rdonly(sb)) {
+ struct fs_context *fc;
+
+ fc = fs_context_for_reconfigure(sb->s_root, SB_RDONLY,
+ SB_RDONLY);
+ if (IS_ERR(fc)) {
+ ret = PTR_ERR(fc);
+ } else {
+ ret = parse_monolithic_mount_data(fc, NULL);
+ if (!ret)
+ ret = reconfigure_super(fc);
+ put_fs_context(fc);
+ }
+ }
+ up_write(&sb->s_umount);
+ return ret;
+}
+
static int do_umount(struct mount *mnt, int flags)
{
struct super_block *sb = mnt->mnt.mnt_sb;
@@ -1554,11 +1577,7 @@ static int do_umount(struct mount *mnt, int flags)
*/
if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN))
return -EPERM;
- down_write(&sb->s_umount);
- if (!sb_rdonly(sb))
- retval = do_remount_sb(sb, SB_RDONLY, NULL, 0);
- up_write(&sb->s_umount);
- return retval;
+ return do_umount_root(sb);
}
namespace_lock();
@@ -2367,7 +2386,7 @@ static int do_remount(struct path *path, int ms_flags, int sb_flags,
int err;
struct super_block *sb = path->mnt->mnt_sb;
struct mount *mnt = real_mount(path->mnt);
- void *sec_opts = NULL;
+ struct fs_context *fc;
if (!check_mnt(mnt))
return -EINVAL;
@@ -2378,24 +2397,22 @@ static int do_remount(struct path *path, int ms_flags, int sb_flags,
if (!can_change_locked_flags(mnt, mnt_flags))
return -EPERM;
- if (data && !(sb->s_type->fs_flags & FS_BINARY_MOUNTDATA)) {
- err = security_sb_eat_lsm_opts(data, &sec_opts);
- if (err)
- return err;
- }
- err = security_sb_remount(sb, sec_opts);
- security_free_mnt_opts(&sec_opts);
- if (err)
- return err;
+ fc = fs_context_for_reconfigure(path->dentry, sb_flags, MS_RMT_MASK);
+ if (IS_ERR(fc))
+ return PTR_ERR(fc);
- down_write(&sb->s_umount);
- err = -EPERM;
- if (ns_capable(sb->s_user_ns, CAP_SYS_ADMIN)) {
- err = do_remount_sb(sb, sb_flags, data, 0);
- if (!err)
- set_mount_attributes(mnt, mnt_flags);
+ err = parse_monolithic_mount_data(fc, data);
+ if (!err) {
+ down_write(&sb->s_umount);
+ err = -EPERM;
+ if (ns_capable(sb->s_user_ns, CAP_SYS_ADMIN)) {
+ err = reconfigure_super(fc);
+ if (!err)
+ set_mount_attributes(mnt, mnt_flags);
+ }
+ up_write(&sb->s_umount);
}
- up_write(&sb->s_umount);
+ put_fs_context(fc);
return err;
}