+++ /dev/null
-Prevent an ext4 filesystem from being mounted multiple times.
-A sequence number is stored on disk and is periodically updated (every 5
-seconds by default) by a mounted filesystem.
-At mount time, we now wait for s_mmp_update_interval seconds to make sure
-that the MMP sequence does not change.
-In case of failure, the nodename, bdevname and the time at which the MMP
-block was last updated is displayed.
-Move all mmp code to a dedicated file (mmp.c).
-
-Signed-off-by: Andreas Dilger <adilger <at> whamcloud.com>
-Signed-off-by: Johann Lombardi <johann <at> whamcloud.com>
----
- fs/ext4/Makefile | 3 +-
- fs/ext4/ext4.h | 76 ++++++++++++-
- fs/ext4/mmp.c | 354 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
- fs/ext4/super.c | 18 +++-
- 4 files changed, 447 insertions(+), 4 deletions(-)
- create mode 100644 fs/ext4/mmp.c
-
-Index: linux-stage/fs/ext4/Makefile
-===================================================================
---- linux-stage.orig/fs/ext4/Makefile
-+++ linux-stage/fs/ext4/Makefile
-@@ -6,7 +6,8 @@ obj-$(CONFIG_EXT4_FS) += ext4.o
-
- ext4-y := balloc.o bitmap.o dir.o file.o fsync.o ialloc.o inode.o \
- ioctl.o namei.o super.o symlink.o hash.o resize.o extents.o \
-- ext4_jbd2.o migrate.o mballoc.o block_validity.o move_extent.o
-+ ext4_jbd2.o migrate.o mballoc.o block_validity.o move_extent.o \
-+ mmp.o
-
- ext4-$(CONFIG_EXT4_FS_XATTR) += xattr.o xattr_user.o xattr_trusted.o
- ext4-$(CONFIG_EXT4_FS_POSIX_ACL) += acl.o
-Index: linux-stage/fs/ext4/ext4.h
-===================================================================
---- linux-stage.orig/fs/ext4/ext4.h
-+++ linux-stage/fs/ext4/ext4.h
-@@ -1009,7 +1009,7 @@ struct ext4_super_block {
- __le16 s_want_extra_isize; /* New inodes should reserve # bytes */
- __le32 s_flags; /* Miscellaneous flags */
- __le16 s_raid_stride; /* RAID stride */
-- __le16 s_mmp_interval; /* # seconds to wait in MMP checking */
-+ __le16 s_mmp_update_interval; /* # seconds to wait in MMP checking */
- __le64 s_mmp_block; /* Block for multi-mount protection */
- __le32 s_raid_stripe_width; /* blocks on all data disks (N*stride)*/
- __u8 s_log_groups_per_flex; /* FLEX_BG group size */
-@@ -1177,6 +1177,9 @@ struct ext4_sb_info {
- /* workqueue for dio unwritten */
- struct workqueue_struct *dio_unwritten_wq;
-
-+ /* Kernel thread for multiple mount protection */
-+ struct task_struct *s_mmp_tsk;
-+
- /* Lazy inode table initialization info */
- struct ext4_li_request *s_li_request;
- /* Wait multiplier for lazy initialization thread */
-@@ -1322,7 +1325,8 @@ EXT4_INODE_BIT_FNS(state, state_flags)
- EXT4_FEATURE_INCOMPAT_META_BG| \
- EXT4_FEATURE_INCOMPAT_EXTENTS| \
- EXT4_FEATURE_INCOMPAT_64BIT| \
-- EXT4_FEATURE_INCOMPAT_FLEX_BG)
-+ EXT4_FEATURE_INCOMPAT_FLEX_BG| \
-+ EXT4_FEATURE_INCOMPAT_MMP)
- #define EXT4_FEATURE_RO_COMPAT_SUPP (EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER| \
- EXT4_FEATURE_RO_COMPAT_LARGE_FILE| \
- EXT4_FEATURE_RO_COMPAT_GDT_CSUM| \
-@@ -1576,6 +1580,67 @@ struct ext4_features {
- };
-
- /*
-+ * This structure will be used for multiple mount protection. It will be
-+ * written into the block number saved in the s_mmp_block field in the
-+ * superblock. Programs that check MMP should assume that if
-+ * SEQ_FSCK (or any unknown code above SEQ_MAX) is present then it is NOT safe
-+ * to use the filesystem, regardless of how old the timestamp is.
-+ */
-+#define EXT4_MMP_MAGIC 0x004D4D50U /* ASCII for MMP */
-+#define EXT4_MMP_SEQ_CLEAN 0xFF4D4D50U /* mmp_seq value for clean unmount */
-+#define EXT4_MMP_SEQ_FSCK 0xE24D4D50U /* mmp_seq value when being fscked */
-+#define EXT4_MMP_SEQ_MAX 0xE24D4D4FU /* maximum valid mmp_seq value */
-+
-+struct mmp_struct {
-+ __le32 mmp_magic; /* Magic number for MMP */
-+ __le32 mmp_seq; /* Sequence no. updated periodically */
-+
-+ /*
-+ * mmp_time, mmp_nodename & mmp_bdevname are only used for information
-+ * purposes and do not affect the correctness of the algorithm
-+ */
-+ __le64 mmp_time; /* Time last updated */
-+ char mmp_nodename[64]; /* Node which last updated MMP block */
-+ char mmp_bdevname[32]; /* Bdev which last updated MMP block */
-+
-+ /*
-+ * mmp_check_interval is used to verify if the MMP block has been
-+ * updated on the block device. The value is updated based on the
-+ * maximum time to write the MMP block during an update cycle.
-+ */
-+ __le16 mmp_check_interval;
-+
-+ __le16 mmp_pad1;
-+ __le32 mmp_pad2[227];
-+};
-+
-+/* arguments passed to the mmp thread */
-+struct mmpd_data {
-+ struct buffer_head *bh; /* bh from initial read_mmp_block() */
-+ struct super_block *sb; /* super block of the fs */
-+};
-+
-+/*
-+ * Check interval multiplier
-+ * The MMP block is written every update interval and initially checked every
-+ * update interval x the multiplier (the value is then adapted based on the
-+ * write latency). The reason is that writes can be delayed under load and we
-+ * don't want readers to incorrectly assume that the filesystem is no longer
-+ * in use.
-+ */
-+#define EXT4_MMP_CHECK_MULT 2UL
-+
-+/*
-+ * Minimum interval for MMP checking in seconds.
-+ */
-+#define EXT4_MMP_MIN_CHECK_INTERVAL 5UL
-+
-+/*
-+ * Maximum interval for MMP checking in seconds.
-+ */
-+#define EXT4_MMP_MAX_CHECK_INTERVAL 300UL
-+
-+/*
- * Function prototypes
- */
-
-@@ -1757,6 +1822,10 @@ extern void __ext4_warning(struct super_
- #define ext4_warning(sb, message...) __ext4_warning(sb, __func__, ## message)
- extern void ext4_msg(struct super_block *, const char *, const char *, ...)
- __attribute__ ((format (printf, 3, 4)));
-+extern void __dump_mmp_msg(struct super_block *, struct mmp_struct *mmp,
-+ const char *, const char *);
-+#define dump_mmp_msg(sb, mmp, msg) __dump_mmp_msg(sb, mmp, __func__, \
-+ msg)
- extern void ext4_grp_locked_error(struct super_block *, ext4_group_t,
- const char *, const char *, ...)
- __attribute__ ((format (printf, 4, 5)));
-@@ -2050,6 +2119,8 @@ extern int ext4_move_extents(struct file
- __u64 start_orig, __u64 start_donor,
- __u64 len, __u64 *moved_len);
-
-+/* mmp.c */
-+extern int ext4_multi_mount_protect(struct super_block *, ext4_fsblk_t);
-
- /*
- * Add new method to test wether block and inode bitmaps are properly
-Index: linux-stage/fs/ext4/mmp.c
-===================================================================
---- /dev/null
-+++ linux-stage/fs/ext4/mmp.c
-@@ -0,0 +1,357 @@
-+#include <linux/fs.h>
-+#include <linux/random.h>
-+#include <linux/buffer_head.h>
-+#include <linux/utsname.h>
-+#include <linux/kthread.h>
-+
-+#include "ext4.h"
-+
-+/*
-+ * Write the MMP block using WRITE_SYNC to try to get the block on-disk
-+ * faster.
-+ */
-+static int write_mmp_block(struct buffer_head *bh)
-+{
-+ mark_buffer_dirty(bh);
-+ lock_buffer(bh);
-+ bh->b_end_io = end_buffer_write_sync;
-+ get_bh(bh);
-+ submit_bh(WRITE_SYNC, bh);
-+ wait_on_buffer(bh);
-+ if (unlikely(!buffer_uptodate(bh)))
-+ return 1;
-+
-+ return 0;
-+}
-+
-+/*
-+ * Read the MMP block. It _must_ be read from disk and hence we clear the
-+ * uptodate flag on the buffer.
-+ */
-+static int read_mmp_block(struct super_block *sb, struct buffer_head **bh,
-+ ext4_fsblk_t mmp_block)
-+{
-+ struct mmp_struct *mmp;
-+
-+ if (*bh)
-+ clear_buffer_uptodate(*bh);
-+
-+ /* This would be sb_bread(sb, mmp_block), except we need to be sure
-+ * that the MD RAID device cache has been bypassed, and that the read
-+ * is not blocked in the elevator. */
-+ if (!*bh)
-+ *bh = sb_getblk(sb, mmp_block);
-+ if (*bh) {
-+ get_bh(*bh);
-+ lock_buffer(*bh);
-+ (*bh)->b_end_io = end_buffer_read_sync;
-+ submit_bh(READ_SYNC, *bh);
-+ wait_on_buffer(*bh);
-+ if (!buffer_uptodate(*bh)) {
-+ brelse(*bh);
-+ *bh = NULL;
-+ }
-+ }
-+ if (!*bh) {
-+ ext4_warning(sb, "Error while reading MMP block %llu",
-+ mmp_block);
-+ return -EIO;
-+ }
-+
-+ mmp = (struct mmp_struct *)((*bh)->b_data);
-+ if (le32_to_cpu(mmp->mmp_magic) != EXT4_MMP_MAGIC) {
-+ brelse(*bh);
-+ *bh = NULL;
-+ return -EINVAL;
-+ }
-+
-+ return 0;
-+}
-+
-+/*
-+ * Dump as much information as possible to help the admin.
-+ */
-+void __dump_mmp_msg(struct super_block *sb, struct mmp_struct *mmp,
-+ const char *function, const char *msg)
-+{
-+ __ext4_warning(sb, function, msg);
-+ __ext4_warning(sb, function,
-+ "MMP failure info: last update time: %llu, last update "
-+ "node: %s, last update device: %s\n",
-+ (long long unsigned int) le64_to_cpu(mmp->mmp_time),
-+ mmp->mmp_nodename, mmp->mmp_bdevname);
-+}
-+
-+/*
-+ * kmmpd will update the MMP sequence every s_mmp_update_interval seconds
-+ */
-+static int kmmpd(void *data)
-+{
-+ struct super_block *sb = ((struct mmpd_data *) data)->sb;
-+ struct buffer_head *bh = ((struct mmpd_data *) data)->bh;
-+ struct ext4_super_block *es = EXT4_SB(sb)->s_es;
-+ struct mmp_struct *mmp;
-+ ext4_fsblk_t mmp_block;
-+ u32 seq = 0;
-+ unsigned long failed_writes = 0;
-+ int mmp_update_interval = le16_to_cpu(es->s_mmp_update_interval);
-+ unsigned mmp_check_interval;
-+ unsigned long last_update_time;
-+ unsigned long diff;
-+ int retval;
-+
-+ mmp_block = le64_to_cpu(es->s_mmp_block);
-+ mmp = (struct mmp_struct *)(bh->b_data);
-+ mmp->mmp_time = cpu_to_le64(get_seconds());
-+ /*
-+ * Start with the higher mmp_check_interval and reduce it if
-+ * the MMP block is being updated on time.
-+ */
-+ mmp_check_interval = max(EXT4_MMP_CHECK_MULT * mmp_update_interval,
-+ EXT4_MMP_MIN_CHECK_INTERVAL);
-+ mmp->mmp_check_interval = cpu_to_le16(mmp_check_interval);
-+ bdevname(bh->b_bdev, mmp->mmp_bdevname);
-+
-+ memcpy(mmp->mmp_nodename, init_utsname()->nodename,
-+ sizeof(mmp->mmp_nodename));
-+
-+ while (!kthread_should_stop()) {
-+ if (++seq > EXT4_MMP_SEQ_MAX)
-+ seq = 1;
-+
-+ mmp->mmp_seq = cpu_to_le32(seq);
-+ mmp->mmp_time = cpu_to_le64(get_seconds());
-+ last_update_time = jiffies;
-+
-+ retval = write_mmp_block(bh);
-+ /*
-+ * Don't spew too many error messages. Print one every
-+ * (s_mmp_update_interval * 60) seconds.
-+ */
-+ if (retval) {
-+ if ((failed_writes % 60) == 0)
-+ ext4_error(sb, "Error writing to MMP block");
-+ failed_writes++;
-+ }
-+
-+ if (!(le32_to_cpu(es->s_feature_incompat) &
-+ EXT4_FEATURE_INCOMPAT_MMP)) {
-+ ext4_warning(sb, "kmmpd being stopped since MMP feature"
-+ " has been disabled.");
-+ EXT4_SB(sb)->s_mmp_tsk = NULL;
-+ goto failed;
-+ }
-+
-+ if (sb->s_flags & MS_RDONLY) {
-+ ext4_warning(sb, "kmmpd being stopped since filesystem "
-+ "has been remounted as readonly.");
-+ EXT4_SB(sb)->s_mmp_tsk = NULL;
-+ goto failed;
-+ }
-+
-+ diff = jiffies - last_update_time;
-+ if (diff < mmp_update_interval * msecs_to_jiffies(MSEC_PER_SEC))
-+ schedule_timeout_interruptible(mmp_update_interval *
-+ msecs_to_jiffies(MSEC_PER_SEC) - diff);
-+
-+ /*
-+ * We need to make sure that more than mmp_check_interval
-+ * seconds have not passed since writing. If that has happened
-+ * we need to check if the MMP block is as we left it.
-+ */
-+ diff = jiffies - last_update_time;
-+ if (diff > mmp_check_interval * msecs_to_jiffies(MSEC_PER_SEC)) {
-+ struct buffer_head *bh_check = NULL;
-+ struct mmp_struct *mmp_check;
-+
-+ retval = read_mmp_block(sb, &bh_check, mmp_block);
-+ if (retval) {
-+ ext4_error(sb, "error reading MMP data: %d",
-+ retval);
-+ EXT4_SB(sb)->s_mmp_tsk = NULL;
-+ goto failed;
-+ }
-+
-+ mmp_check = (struct mmp_struct *)(bh_check->b_data);
-+ if (mmp->mmp_seq != mmp_check->mmp_seq ||
-+ memcmp(mmp->mmp_nodename, mmp_check->mmp_nodename,
-+ sizeof(mmp->mmp_nodename))) {
-+ dump_mmp_msg(sb, mmp_check,
-+ "Error while updating MMP info. "
-+ "The filesystem seems to have been"
-+ " multiply mounted.");
-+ ext4_error(sb, "abort");
-+ put_bh(bh_check);
-+ goto failed;
-+ }
-+ put_bh(bh_check);
-+ }
-+
-+ /*
-+ * Adjust the mmp_check_interval depending on how much time
-+ * it took for the MMP block to be written.
-+ */
-+ mmp_check_interval = max(min(EXT4_MMP_CHECK_MULT * diff /
-+ msecs_to_jiffies(MSEC_PER_SEC),
-+ EXT4_MMP_MAX_CHECK_INTERVAL),
-+ EXT4_MMP_MIN_CHECK_INTERVAL);
-+ mmp->mmp_check_interval = cpu_to_le16(mmp_check_interval);
-+ }
-+
-+ /*
-+ * Unmount seems to be clean.
-+ */
-+ mmp->mmp_seq = cpu_to_le32(EXT4_MMP_SEQ_CLEAN);
-+ mmp->mmp_time = cpu_to_le64(get_seconds());
-+
-+ retval = write_mmp_block(bh);
-+
-+failed:
-+ kfree(data);
-+ brelse(bh);
-+ return retval;
-+}
-+
-+/*
-+ * Get a random new sequence number but make sure it is not greater than
-+ * EXT4_MMP_SEQ_MAX.
-+ */
-+static unsigned int mmp_new_seq(void)
-+{
-+ u32 new_seq;
-+
-+ do {
-+ get_random_bytes(&new_seq, sizeof(u32));
-+ } while (new_seq > EXT4_MMP_SEQ_MAX);
-+
-+ return new_seq;
-+}
-+
-+/*
-+ * Protect the filesystem from being mounted more than once.
-+ */
-+int ext4_multi_mount_protect(struct super_block *sb,
-+ ext4_fsblk_t mmp_block)
-+{
-+ struct ext4_super_block *es = EXT4_SB(sb)->s_es;
-+ struct buffer_head *bh = NULL;
-+ struct mmp_struct *mmp = NULL;
-+ struct mmpd_data *mmpd_data;
-+ u32 seq;
-+ unsigned int mmp_check_interval = le16_to_cpu(es->s_mmp_update_interval);
-+ unsigned int wait_time = 0;
-+ int retval;
-+
-+ if (mmp_block < le32_to_cpu(es->s_first_data_block) ||
-+ mmp_block >= ext4_blocks_count(es)) {
-+ ext4_warning(sb, "Invalid MMP block in superblock");
-+ goto failed;
-+ }
-+
-+ retval = read_mmp_block(sb, &bh, mmp_block);
-+ if (retval)
-+ goto failed;
-+
-+ mmp = (struct mmp_struct *)(bh->b_data);
-+
-+ if (mmp_check_interval < EXT4_MMP_MIN_CHECK_INTERVAL)
-+ mmp_check_interval = EXT4_MMP_MIN_CHECK_INTERVAL;
-+
-+ /*
-+ * If check_interval in MMP block is larger, use that instead of
-+ * update_interval from the superblock.
-+ */
-+ if (mmp->mmp_check_interval > mmp_check_interval)
-+ mmp_check_interval = mmp->mmp_check_interval;
-+
-+ seq = le32_to_cpu(mmp->mmp_seq);
-+ if (seq == EXT4_MMP_SEQ_CLEAN)
-+ goto skip;
-+
-+ if (seq == EXT4_MMP_SEQ_FSCK) {
-+ dump_mmp_msg(sb, mmp, "fsck is running on the filesystem");
-+ goto failed;
-+ }
-+
-+ wait_time = min(mmp_check_interval * 2 + 1,
-+ mmp_check_interval + 60);
-+
-+ /* Print MMP interval if more than 20 secs. */
-+ if (wait_time > EXT4_MMP_MIN_CHECK_INTERVAL * 4)
-+ ext4_warning(sb, "MMP interval %u higher than expected, please"
-+ " wait.\n", wait_time * 2);
-+
-+ if (schedule_timeout_interruptible(msecs_to_jiffies(MSEC_PER_SEC) *
-+ wait_time) != 0) {
-+ ext4_warning(sb, "MMP startup interrupted, failing mount\n");
-+ goto failed;
-+ }
-+
-+ retval = read_mmp_block(sb, &bh, mmp_block);
-+ if (retval)
-+ goto failed;
-+ mmp = (struct mmp_struct *)(bh->b_data);
-+ if (seq != le32_to_cpu(mmp->mmp_seq)) {
-+ dump_mmp_msg(sb, mmp,
-+ "Device is already active on another node.");
-+ goto failed;
-+ }
-+
-+skip:
-+ /*
-+ * write a new random sequence number.
-+ */
-+ mmp->mmp_seq = seq = cpu_to_le32(mmp_new_seq());
-+
-+ retval = write_mmp_block(bh);
-+ if (retval)
-+ goto failed;
-+
-+ /*
-+ * wait for MMP interval and check mmp_seq.
-+ */
-+ if (schedule_timeout_interruptible(msecs_to_jiffies(MSEC_PER_SEC) *
-+ wait_time) != 0) {
-+ ext4_warning(sb, "MMP startup interrupted, failing mount\n");
-+ goto failed;
-+ }
-+
-+ retval = read_mmp_block(sb, &bh, mmp_block);
-+ if (retval)
-+ goto failed;
-+ mmp = (struct mmp_struct *)(bh->b_data);
-+ if (seq != le32_to_cpu(mmp->mmp_seq)) {
-+ dump_mmp_msg(sb, mmp,
-+ "Device is already active on another node.");
-+ goto failed;
-+ }
-+
-+ mmpd_data = kmalloc(sizeof(struct mmpd_data), GFP_KERNEL);
-+ if (!mmpd_data) {
-+ ext4_warning(sb, "not enough memory for mmpd_data");
-+ goto failed;
-+ }
-+ mmpd_data->sb = sb;
-+ mmpd_data->bh = bh;
-+
-+ /*
-+ * Start a kernel thread to update the MMP block periodically.
-+ */
-+ EXT4_SB(sb)->s_mmp_tsk = kthread_run(kmmpd, mmpd_data, "kmmpd-%s",
-+ bdevname(bh->b_bdev,
-+ mmp->mmp_bdevname));
-+ if (IS_ERR(EXT4_SB(sb)->s_mmp_tsk)) {
-+ EXT4_SB(sb)->s_mmp_tsk = NULL;
-+ kfree(mmpd_data);
-+ ext4_warning(sb, "Unable to create kmmpd thread for %s.",
-+ sb->s_id);
-+ goto failed;
-+ }
-+
-+ return 0;
-+
-+failed:
-+ brelse(bh);
-+ return 1;
-+}
-+
-Index: linux-stage/fs/ext4/super.c
-===================================================================
---- linux-stage.orig/fs/ext4/super.c
-+++ linux-stage/fs/ext4/super.c
-@@ -40,6 +40,8 @@
- #include <linux/log2.h>
- #include <linux/crc16.h>
- #include <asm/uaccess.h>
-+#include <linux/kthread.h>
-+#include <linux/utsname.h>
-
- #include <linux/kthread.h>
- #include <linux/freezer.h>
-@@ -716,6 +718,8 @@ static void ext4_put_super(struct super_
- invalidate_bdev(sbi->journal_bdev);
- ext4_blkdev_remove(sbi);
- }
-+ if (sbi->s_mmp_tsk)
-+ kthread_stop(sbi->s_mmp_tsk);
- sb->s_fs_info = NULL;
- /*
- * Now that we are completely done shutting down the
-@@ -3241,6 +3245,10 @@ static int ext4_fill_super(struct super_
- needs_recovery = (es->s_last_orphan != 0 ||
- EXT4_HAS_INCOMPAT_FEATURE(sb,
- EXT4_FEATURE_INCOMPAT_RECOVER));
-+ if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_MMP) &&
-+ !(sb->s_flags & MS_RDONLY))
-+ if (ext4_multi_mount_protect(sb, le64_to_cpu(es->s_mmp_block)))
-+ goto failed_mount3;
-
- /*
- * The first inode we look at is the journal inode. Don't try
-@@ -3491,6 +3499,8 @@ failed_mount3:
- percpu_counter_destroy(&sbi->s_freeinodes_counter);
- percpu_counter_destroy(&sbi->s_dirs_counter);
- percpu_counter_destroy(&sbi->s_dirtyblocks_counter);
-+ if (sbi->s_mmp_tsk)
-+ kthread_stop(sbi->s_mmp_tsk);
- failed_mount2:
- for (i = 0; i < db_count; i++)
- brelse(sbi->s_group_desc[i]);
-@@ -4001,7 +4011,7 @@ static int ext4_remount(struct super_blo
- int enable_quota = 0;
- ext4_group_t g;
- unsigned int journal_ioprio = DEFAULT_JOURNAL_IOPRIO;
-- int err;
-+ int err = 0;
- #ifdef CONFIG_QUOTA
- int i;
- #endif
-@@ -4129,6 +4139,13 @@ static int ext4_remount(struct super_blo
- goto restore_opts;
- if (!ext4_setup_super(sb, es, 0))
- sb->s_flags &= ~MS_RDONLY;
-+ if (EXT4_HAS_INCOMPAT_FEATURE(sb,
-+ EXT4_FEATURE_INCOMPAT_MMP))
-+ if (ext4_multi_mount_protect(sb,
-+ le64_to_cpu(es->s_mmp_block))) {
-+ err = -EROFS;
-+ goto restore_opts;
-+ }
- enable_quota = 1;
- }
- }
git://git.whamcloud.com / fs / lustre-release.git / blobdiff