Introduce a new mount option "nologreplay" to co-operate with "ro" mount
option to get real readonly mount, like "norecovery" in ext* and xfs.
Since the new parse_options() need to check new flags at remount time,
so add a new parameter for parse_options().
Signed-off-by: Qu Wenruo <quwen...@cn.fujitsu.com>
Reviewed-by: Chandan Rajendra <chan...@linux.vnet.ibm.com>
Tested-by: Austin S. Hemmelgarn <ahferro...@gmail.com>
---
v2:
Make RO check mandatory for btrfs_parse_options().
Add btrfs_show_options() support for nologreplay.
Document for btrfs-mount(5) will follow after the patch being merged.
v3:
Apply the document suggestion from Chandan Rajendra.
---
Documentation/filesystems/btrfs.txt | 9 +++++++++
fs/btrfs/ctree.h | 4 +++-
fs/btrfs/disk-io.c | 7 ++++---
fs/btrfs/super.c | 29 +++++++++++++++++++++++++----
4 files changed, 41 insertions(+), 8 deletions(-)
diff --git a/Documentation/filesystems/btrfs.txt
b/Documentation/filesystems/btrfs.txt
index c772b47..0f2ed48 100644
--- a/Documentation/filesystems/btrfs.txt
+++ b/Documentation/filesystems/btrfs.txt
@@ -168,6 +168,15 @@ Options with (*) are default options and will not show in
the mount options.
notreelog
Enable/disable the tree logging used for fsync and O_SYNC writes.
+ nologreplay
+ Disable the log tree replay at mount time to prevent filesystem
+ from getting modified.
+ Must be used with 'ro' mount option.
+ A filesystem mounted with the 'nologreplay' option cannot
+ transition to a read-write mount via remount,rw - the filesystem
+ must be unmounted and mounted back again if read-write access is
+ desired.
+
recovery
Enable autorecovery attempts if a bad tree root is found at mount time.
Currently this scans a list of several previous tree roots and tries to
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index a0165c6..c54ff25 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2184,6 +2184,7 @@ struct btrfs_ioctl_defrag_range_args {
#define BTRFS_MOUNT_RESCAN_UUID_TREE (1 << 23)
#define BTRFS_MOUNT_FRAGMENT_DATA (1 << 24)
#define BTRFS_MOUNT_FRAGMENT_METADATA (1 << 25)
+#define BTRFS_MOUNT_NOLOGREPLAY (1 << 26)
#define BTRFS_DEFAULT_COMMIT_INTERVAL (30)
#define BTRFS_DEFAULT_MAX_INLINE (8192)
@@ -4070,7 +4071,8 @@ void btrfs_sysfs_remove_mounted(struct btrfs_fs_info
*fs_info);
ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size);
/* super.c */
-int btrfs_parse_options(struct btrfs_root *root, char *options);
+int btrfs_parse_options(struct btrfs_root *root, char *options,
+ unsigned long new_flags);
int btrfs_sync_fs(struct super_block *sb, int wait);
#ifdef CONFIG_PRINTK
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 1eb0839..617bf4f 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2711,7 +2711,7 @@ int open_ctree(struct super_block *sb,
*/
fs_info->compress_type = BTRFS_COMPRESS_ZLIB;
- ret = btrfs_parse_options(tree_root, options);
+ ret = btrfs_parse_options(tree_root, options, sb->s_flags);
if (ret) {
err = ret;
goto fail_alloc;
@@ -3009,8 +3009,9 @@ retry_root_backup:
if (ret)
goto fail_trans_kthread;
- /* do not make disk changes in broken FS */
- if (btrfs_super_log_root(disk_super) != 0) {
+ /* do not make disk changes in broken FS or nologreplay is given */
+ if (btrfs_super_log_root(disk_super) != 0 &&
+ !btrfs_test_opt(tree_root, NOLOGREPLAY)) {
ret = btrfs_replay_log(fs_info, fs_devices);
if (ret) {
err = ret;
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 24154e4..55989cb 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -302,7 +302,7 @@ enum {
Opt_check_integrity_print_mask, Opt_fatal_errors, Opt_rescan_uuid_tree,
Opt_commit_interval, Opt_barrier, Opt_nodefrag, Opt_nodiscard,
Opt_noenospc_debug, Opt_noflushoncommit, Opt_acl, Opt_datacow,
- Opt_datasum, Opt_treelog, Opt_noinode_cache,
+ Opt_datasum, Opt_treelog, Opt_noinode_cache, Opt_nologreplay,
#ifdef CONFIG_BTRFS_DEBUG
Opt_fragment_data, Opt_fragment_metadata, Opt_fragment_all,
#endif
@@ -334,6 +334,7 @@ static match_table_t tokens = {
{Opt_noacl, "noacl"},
{Opt_notreelog, "notreelog"},
{Opt_treelog, "treelog"},
+ {Opt_nologreplay, "nologreplay"},
{Opt_flushoncommit, "flushoncommit"},
{Opt_noflushoncommit, "noflushoncommit"},
{Opt_ratio, "metadata_ratio=%d"},
@@ -371,7 +372,8 @@ static match_table_t tokens = {
* reading in a new superblock is parsed here.
* XXX JDM: This needs to be cleaned up for remount.
*/
-int btrfs_parse_options(struct btrfs_root *root, char *options)
+int btrfs_parse_options(struct btrfs_root *root, char *options,
+ unsigned long new_flags)
{
struct btrfs_fs_info *info = root->fs_info;
substring_t args[MAX_OPT_ARGS];
@@ -386,8 +388,12 @@ int btrfs_parse_options(struct btrfs_root *root, char
*options)
if (cache_gen)
btrfs_set_opt(info->mount_opt, SPACE_CACHE);
+ /*
+ * Even the options are empty, we still need to do extra check
+ * against new flags
+ */
if (!options)
- goto out;
+ goto check;
/*
* strsep changes the string, duplicate it because parse_options
@@ -587,6 +593,10 @@ int btrfs_parse_options(struct btrfs_root *root, char
*options)
btrfs_clear_and_info(root, NOTREELOG,
"enabling tree log");
break;
+ case Opt_nologreplay:
+ btrfs_set_and_info(root, NOLOGREPLAY,
+ "disabling log replay at mount
time");
+ break;
case Opt_flushoncommit:
btrfs_set_and_info(root, FLUSHONCOMMIT,
"turning on flush-on-commit");
@@ -753,6 +763,15 @@ int btrfs_parse_options(struct btrfs_root *root, char
*options)
break;
}
}
+check:
+ /*
+ * Extra check for current option against current flag
+ */
+ if (btrfs_test_opt(root, NOLOGREPLAY) && !(new_flags & MS_RDONLY)) {
+ btrfs_err(root->fs_info,
+ "nologreplay must be used with ro mount option");
+ ret = -EINVAL;
+ }
out:
if (!ret && btrfs_test_opt(root, SPACE_CACHE))
btrfs_info(root->fs_info, "disk space caching is enabled");
@@ -1154,6 +1173,8 @@ static int btrfs_show_options(struct seq_file *seq,
struct dentry *dentry)
seq_puts(seq, ",ssd");
if (btrfs_test_opt(root, NOTREELOG))
seq_puts(seq, ",notreelog");
+ if (btrfs_test_opt(root, NOLOGREPLAY))
+ seq_puts(seq, ",nologreplay");
if (btrfs_test_opt(root, FLUSHONCOMMIT))
seq_puts(seq, ",flushoncommit");
if (btrfs_test_opt(root, DISCARD))
@@ -1637,7 +1658,7 @@ static int btrfs_remount(struct super_block *sb, int
*flags, char *data)
}
}
- ret = btrfs_parse_options(root, data);
+ ret = btrfs_parse_options(root, data, *flags);
if (ret) {
ret = -EINVAL;
goto restore;
--
2.6.3
--
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