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-rw-r--r--fs/ext4/ext4.h76
1 files changed, 74 insertions, 2 deletions
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 65fe1dc0c750..c0c56c9d5933 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1028,7 +1028,7 @@ 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 */
@@ -1204,6 +1204,9 @@ struct ext4_sb_info {
struct ext4_li_request *s_li_request;
/* Wait multiplier for lazy initialization thread */
unsigned int s_li_wait_mult;
+
+ /* Kernel thread for multiple mount protection */
+ struct task_struct *s_mmp_tsk;
};
static inline struct ext4_sb_info *EXT4_SB(struct super_block *sb)
@@ -1375,7 +1378,8 @@ static inline void ext4_clear_state_flags(struct ext4_inode_info *ei)
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| \
@@ -1627,6 +1631,67 @@ 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
*/
@@ -1800,6 +1865,10 @@ extern void __ext4_warning(struct super_block *, const char *, unsigned int,
__LINE__, ## 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 *, unsigned int, const char *);
+#define dump_mmp_msg(sb, mmp, msg) __dump_mmp_msg(sb, mmp, __func__, \
+ __LINE__, msg)
extern void __ext4_grp_locked_error(const char *, unsigned int, \
struct super_block *, ext4_group_t, \
unsigned long, ext4_fsblk_t, \
@@ -2104,6 +2173,9 @@ extern int ext4_bio_write_page(struct ext4_io_submit *io,
int len,
struct writeback_control *wbc);
+/* mmp.c */
+extern int ext4_multi_mount_protect(struct super_block *, ext4_fsblk_t);
+
/* BH_Uninit flag: blocks are allocated but uninitialized on disk */
enum ext4_state_bits {
BH_Uninit /* blocks are allocated but uninitialized on disk */