From 96da09192cda57a356467bd7c91a3641a2e78490 Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Tue, 19 Jan 2016 10:23:03 +0800 Subject: [PATCH] btrfs: Introduce new mount option to disable tree log replay 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 Reviewed-by: Chandan Rajendra Tested-by: Austin S. Hemmelgarn Signed-off-by: David Sterba --- Documentation/filesystems/btrfs.txt | 8 ++++++++ fs/btrfs/ctree.h | 4 +++- fs/btrfs/disk-io.c | 7 ++++--- fs/btrfs/super.c | 28 +++++++++++++++++++++++++--- 4 files changed, 40 insertions(+), 7 deletions(-) diff --git a/Documentation/filesystems/btrfs.txt b/Documentation/filesystems/btrfs.txt index a2b1c508c32c..6593d2e415c5 100644 --- a/Documentation/filesystems/btrfs.txt +++ b/Documentation/filesystems/btrfs.txt @@ -168,6 +168,14 @@ 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 this 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. + usebackuproot Enable attempts to use backup tree roots if a bad tree root is found at mount time. diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index e39eeb99adc9..a79bb734f6c3 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -2250,6 +2250,7 @@ struct btrfs_ioctl_defrag_range_args { #define BTRFS_MOUNT_FRAGMENT_DATA (1 << 24) #define BTRFS_MOUNT_FRAGMENT_METADATA (1 << 25) #define BTRFS_MOUNT_FREE_SPACE_TREE (1 << 26) +#define BTRFS_MOUNT_NOLOGREPLAY (1 << 27) #define BTRFS_DEFAULT_COMMIT_INTERVAL (30) #define BTRFS_DEFAULT_MAX_INLINE (8192) @@ -4151,7 +4152,8 @@ 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 c0363626c5da..18541dc4ec0b 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2750,7 +2750,7 @@ 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; @@ -3029,8 +3029,9 @@ 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 7ed3863c264b..e8a7a9f88195 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -304,6 +304,7 @@ enum { 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_usebackuproot, + Opt_nologreplay, #ifdef CONFIG_BTRFS_DEBUG Opt_fragment_data, Opt_fragment_metadata, Opt_fragment_all, #endif @@ -335,6 +336,7 @@ static const 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"}, @@ -374,7 +376,8 @@ static const 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]; @@ -394,8 +397,12 @@ int btrfs_parse_options(struct btrfs_root *root, char *options) else 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 @@ -607,6 +614,10 @@ 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"); @@ -797,6 +808,15 @@ 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 (btrfs_fs_compat_ro(root->fs_info, FREE_SPACE_TREE) && !btrfs_test_opt(root, FREE_SPACE_TREE) && @@ -1207,6 +1227,8 @@ 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)) @@ -1688,7 +1710,7 @@ 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;