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authorDavid Howells <dhowells@redhat.com>2018-11-04 09:28:36 -0500
committerAl Viro <viro@zeniv.linux.org.uk>2019-01-30 17:44:26 -0500
commit8d0347f6c3a9d4953ddd636a31c6584da082e084 (patch)
treea8dec0e9d854bad8732ae41084e6f7c980713758 /fs/super.c
parentc9ce29ed795fae86e594844857fad1b0d3be85f4 (diff)
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/super.c')
-rw-r--r--fs/super.c107
1 files changed, 73 insertions, 34 deletions
diff --git a/fs/super.c b/fs/super.c
index 11e2a6cb3baf..50553233dd15 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -836,28 +836,35 @@ rescan:
}
/**
- * do_remount_sb - asks filesystem to change mount options.
- * @sb: superblock in question
- * @sb_flags: revised superblock flags
- * @data: the rest of options
- * @force: whether or not to force the change
+ * reconfigure_super - asks filesystem to change superblock parameters
+ * @fc: The superblock and configuration
*
- * Alters the mount options of a mounted file system.
+ * Alters the configuration parameters of a live superblock.
*/
-int do_remount_sb(struct super_block *sb, int sb_flags, void *data, int force)
+int reconfigure_super(struct fs_context *fc)
{
+ struct super_block *sb = fc->root->d_sb;
int retval;
- int remount_ro;
+ bool remount_ro = false;
+ bool force = fc->sb_flags & SB_FORCE;
+ if (fc->sb_flags_mask & ~MS_RMT_MASK)
+ return -EINVAL;
if (sb->s_writers.frozen != SB_UNFROZEN)
return -EBUSY;
+ retval = security_sb_remount(sb, fc->security);
+ if (retval)
+ return retval;
+
+ if (fc->sb_flags_mask & SB_RDONLY) {
#ifdef CONFIG_BLOCK
- if (!(sb_flags & SB_RDONLY) && bdev_read_only(sb->s_bdev))
- return -EACCES;
+ if (!(fc->sb_flags & SB_RDONLY) && bdev_read_only(sb->s_bdev))
+ return -EACCES;
#endif
- remount_ro = (sb_flags & SB_RDONLY) && !sb_rdonly(sb);
+ remount_ro = (fc->sb_flags & SB_RDONLY) && !sb_rdonly(sb);
+ }
if (remount_ro) {
if (!hlist_empty(&sb->s_pins)) {
@@ -868,13 +875,14 @@ int do_remount_sb(struct super_block *sb, int sb_flags, void *data, int force)
return 0;
if (sb->s_writers.frozen != SB_UNFROZEN)
return -EBUSY;
- remount_ro = (sb_flags & SB_RDONLY) && !sb_rdonly(sb);
+ remount_ro = !sb_rdonly(sb);
}
}
shrink_dcache_sb(sb);
- /* If we are remounting RDONLY and current sb is read/write,
- make sure there are no rw files opened */
+ /* If we are reconfiguring to RDONLY and current sb is read/write,
+ * make sure there are no files open for writing.
+ */
if (remount_ro) {
if (force) {
sb->s_readonly_remount = 1;
@@ -886,17 +894,17 @@ int do_remount_sb(struct super_block *sb, int sb_flags, void *data, int force)
}
}
- if (sb->s_op->remount_fs) {
- retval = sb->s_op->remount_fs(sb, &sb_flags, data);
- if (retval) {
- if (!force)
- goto cancel_readonly;
- /* If forced remount, go ahead despite any errors */
- WARN(1, "forced remount of a %s fs returned %i\n",
- sb->s_type->name, retval);
- }
+ retval = legacy_reconfigure(fc);
+ if (retval) {
+ if (!force)
+ goto cancel_readonly;
+ /* If forced remount, go ahead despite any errors */
+ WARN(1, "forced remount of a %s fs returned %i\n",
+ sb->s_type->name, retval);
}
- sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (sb_flags & MS_RMT_MASK);
+
+ WRITE_ONCE(sb->s_flags, ((sb->s_flags & ~fc->sb_flags_mask) |
+ (fc->sb_flags & fc->sb_flags_mask)));
/* Needs to be ordered wrt mnt_is_readonly() */
smp_wmb();
sb->s_readonly_remount = 0;
@@ -923,10 +931,15 @@ static void do_emergency_remount_callback(struct super_block *sb)
down_write(&sb->s_umount);
if (sb->s_root && sb->s_bdev && (sb->s_flags & SB_BORN) &&
!sb_rdonly(sb)) {
- /*
- * What lock protects sb->s_flags??
- */
- do_remount_sb(sb, SB_RDONLY, NULL, 1);
+ struct fs_context *fc;
+
+ fc = fs_context_for_reconfigure(sb->s_root,
+ SB_RDONLY | SB_FORCE, SB_RDONLY);
+ if (!IS_ERR(fc)) {
+ if (parse_monolithic_mount_data(fc, NULL) == 0)
+ (void)reconfigure_super(fc);
+ put_fs_context(fc);
+ }
}
up_write(&sb->s_umount);
}
@@ -1213,6 +1226,31 @@ struct dentry *mount_nodev(struct file_system_type *fs_type,
}
EXPORT_SYMBOL(mount_nodev);
+static int reconfigure_single(struct super_block *s,
+ int flags, void *data)
+{
+ struct fs_context *fc;
+ int ret;
+
+ /* The caller really need to be passing fc down into mount_single(),
+ * then a chunk of this can be removed. [Bollocks -- AV]
+ * Better yet, reconfiguration shouldn't happen, but rather the second
+ * mount should be rejected if the parameters are not compatible.
+ */
+ fc = fs_context_for_reconfigure(s->s_root, flags, MS_RMT_MASK);
+ if (IS_ERR(fc))
+ return PTR_ERR(fc);
+
+ ret = parse_monolithic_mount_data(fc, data);
+ if (ret < 0)
+ goto out;
+
+ ret = reconfigure_super(fc);
+out:
+ put_fs_context(fc);
+ return ret;
+}
+
static int compare_single(struct super_block *s, void *p)
{
return 1;
@@ -1230,13 +1268,14 @@ struct dentry *mount_single(struct file_system_type *fs_type,
return ERR_CAST(s);
if (!s->s_root) {
error = fill_super(s, data, flags & SB_SILENT ? 1 : 0);
- if (error) {
- deactivate_locked_super(s);
- return ERR_PTR(error);
- }
- s->s_flags |= SB_ACTIVE;
+ if (!error)
+ s->s_flags |= SB_ACTIVE;
} else {
- do_remount_sb(s, flags, data, 0);
+ error = reconfigure_single(s, flags, data);
+ }
+ if (unlikely(error)) {
+ deactivate_locked_super(s);
+ return ERR_PTR(error);
}
return dget(s->s_root);
}