Release 4.15 fs/ext4/mmp.c
// SPDX-License-Identifier: GPL-2.0
#include <linux/fs.h>
#include <linux/random.h>
#include <linux/buffer_head.h>
#include <linux/utsname.h>
#include <linux/kthread.h>
#include "ext4.h"
/* Checksumming functions */
static __le32 ext4_mmp_csum(struct super_block *sb, struct mmp_struct *mmp)
{
struct ext4_sb_info *sbi = EXT4_SB(sb);
int offset = offsetof(struct mmp_struct, mmp_checksum);
__u32 csum;
csum = ext4_chksum(sbi, sbi->s_csum_seed, (char *)mmp, offset);
return cpu_to_le32(csum);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Darrick J. Wong | 64 | 98.46% | 1 | 50.00% |
| Dmitriy Monakhov | 1 | 1.54% | 1 | 50.00% |
| Total | 65 | 100.00% | 2 | 100.00% |
static int ext4_mmp_csum_verify(struct super_block *sb, struct mmp_struct *mmp)
{
if (!ext4_has_metadata_csum(sb))
return 1;
return mmp->mmp_checksum == ext4_mmp_csum(sb, mmp);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Darrick J. Wong | 37 | 94.87% | 1 | 33.33% |
| Dmitriy Monakhov | 1 | 2.56% | 1 | 33.33% |
| Stephen Hemminger | 1 | 2.56% | 1 | 33.33% |
| Total | 39 | 100.00% | 3 | 100.00% |
static void ext4_mmp_csum_set(struct super_block *sb, struct mmp_struct *mmp)
{
if (!ext4_has_metadata_csum(sb))
return;
mmp->mmp_checksum = ext4_mmp_csum(sb, mmp);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Darrick J. Wong | 34 | 94.44% | 1 | 33.33% |
| Stephen Hemminger | 1 | 2.78% | 1 | 33.33% |
| Dmitriy Monakhov | 1 | 2.78% | 1 | 33.33% |
| Total | 36 | 100.00% | 3 | 100.00% |
/*
* Write the MMP block using REQ_SYNC to try to get the block on-disk
* faster.
*/
static int write_mmp_block(struct super_block *sb, struct buffer_head *bh)
{
struct mmp_struct *mmp = (struct mmp_struct *)(bh->b_data);
/*
* We protect against freezing so that we don't create dirty buffers
* on frozen filesystem.
*/
sb_start_write(sb);
ext4_mmp_csum_set(sb, mmp);
mark_buffer_dirty(bh);
lock_buffer(bh);
bh->b_end_io = end_buffer_write_sync;
get_bh(bh);
submit_bh(REQ_OP_WRITE, REQ_SYNC | REQ_META | REQ_PRIO, bh);
wait_on_buffer(bh);
sb_end_write(sb);
if (unlikely(!buffer_uptodate(bh)))
return 1;
return 0;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Johann Lombardi | 60 | 56.60% | 1 | 16.67% |
| Darrick J. Wong | 28 | 26.42% | 1 | 16.67% |
| Jan Kara | 11 | 10.38% | 1 | 16.67% |
| Theodore Y. Ts'o | 4 | 3.77% | 1 | 16.67% |
| Michael Christie | 2 | 1.89% | 1 | 16.67% |
| Christoph Hellwig | 1 | 0.94% | 1 | 16.67% |
| Total | 106 | 100.00% | 6 | 100.00% |
/*
* 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;
int ret;
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) {
ret = -ENOMEM;
goto warn_exit;
}
}
get_bh(*bh);
lock_buffer(*bh);
(*bh)->b_end_io = end_buffer_read_sync;
submit_bh(REQ_OP_READ, REQ_META | REQ_PRIO, *bh);
wait_on_buffer(*bh);
if (!buffer_uptodate(*bh)) {
ret = -EIO;
goto warn_exit;
}
mmp = (struct mmp_struct *)((*bh)->b_data);
if (le32_to_cpu(mmp->mmp_magic) != EXT4_MMP_MAGIC) {
ret = -EFSCORRUPTED;
goto warn_exit;
}
if (!ext4_mmp_csum_verify(sb, mmp)) {
ret = -EFSBADCRC;
goto warn_exit;
}
return 0;
warn_exit:
brelse(*bh);
*bh = NULL;
ext4_warning(sb, "Error %d while reading MMP block %llu",
ret, mmp_block);
return ret;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Johann Lombardi | 131 | 59.82% | 1 | 12.50% |
| Dan Carpenter | 36 | 16.44% | 1 | 12.50% |
| vikram.jadhav07 | 21 | 9.59% | 1 | 12.50% |
| Darrick J. Wong | 20 | 9.13% | 2 | 25.00% |
| Theodore Y. Ts'o | 9 | 4.11% | 2 | 25.00% |
| Michael Christie | 2 | 0.91% | 1 | 12.50% |
| Total | 219 | 100.00% | 8 | 100.00% |
/*
* 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, unsigned int line, const char *msg)
{
__ext4_warning(sb, function, line, "%s", msg);
__ext4_warning(sb, function, line,
"MMP failure info: last update time: %llu, last update "
"node: %s, last update device: %s",
(long long unsigned int) le64_to_cpu(mmp->mmp_time),
mmp->mmp_nodename, mmp->mmp_bdevname);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Johann Lombardi | 72 | 96.00% | 1 | 33.33% |
| Dan Carpenter | 2 | 2.67% | 1 | 33.33% |
| Jakub Wilk | 1 | 1.33% | 1 | 33.33% |
| Total | 75 | 100.00% | 3 | 100.00% |
/*
* 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(sb, 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.");
goto exit_thread;
}
if (sb_rdonly(sb)) {
ext4_warning(sb, "kmmpd being stopped since filesystem "
"has been remounted as readonly.");
goto exit_thread;
}
diff = jiffies - last_update_time;
if (diff < mmp_update_interval * HZ)
schedule_timeout_interruptible(mmp_update_interval *
HZ - 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 * HZ) {
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);
goto exit_thread;
}
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);
retval = -EBUSY;
goto exit_thread;
}
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 / HZ,
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(sb, bh);
exit_thread:
EXT4_SB(sb)->s_mmp_tsk = NULL;
kfree(data);
brelse(bh);
return retval;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Johann Lombardi | 511 | 93.42% | 1 | 16.67% |
| vikram.jadhav07 | 24 | 4.39% | 1 | 16.67% |
| Nikitas Angelinas | 5 | 0.91% | 2 | 33.33% |
| Darrick J. Wong | 4 | 0.73% | 1 | 16.67% |
| David Howells | 3 | 0.55% | 1 | 16.67% |
| Total | 547 | 100.00% | 6 | 100.00% |
/*
* 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 {
new_seq = prandom_u32();
} while (new_seq > EXT4_MMP_SEQ_MAX);
return new_seq;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Johann Lombardi | 27 | 90.00% | 1 | 50.00% |
| Theodore Y. Ts'o | 3 | 10.00% | 1 | 50.00% |
| Total | 30 | 100.00% | 2 | 100.00% |
/*
* 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 (le16_to_cpu(mmp->mmp_check_interval) > mmp_check_interval)
mmp_check_interval = le16_to_cpu(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(HZ * 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.
*/
seq = mmp_new_seq();
mmp->mmp_seq = cpu_to_le32(seq);
retval = write_mmp_block(sb, bh);
if (retval)
goto failed;
/*
* wait for MMP interval and check mmp_seq.
*/
if (schedule_timeout_interruptible(HZ * wait_time) != 0) {
ext4_warning(sb, "MMP startup interrupted, failing mount");
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(*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;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Johann Lombardi | 537 | 97.11% | 1 | 16.67% |
| Darrick J. Wong | 8 | 1.45% | 2 | 33.33% |
| Santosh Nayak | 6 | 1.08% | 1 | 16.67% |
| Jakub Wilk | 1 | 0.18% | 1 | 16.67% |
| SF Markus Elfring | 1 | 0.18% | 1 | 16.67% |
| Total | 553 | 100.00% | 6 | 100.00% |
Overall Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Johann Lombardi | 1361 | 80.25% | 1 | 4.35% |
| Darrick J. Wong | 196 | 11.56% | 3 | 13.04% |
| vikram.jadhav07 | 45 | 2.65% | 1 | 4.35% |
| Dan Carpenter | 38 | 2.24% | 2 | 8.70% |
| Theodore Y. Ts'o | 16 | 0.94% | 3 | 13.04% |
| Jan Kara | 11 | 0.65% | 1 | 4.35% |
| Santosh Nayak | 6 | 0.35% | 1 | 4.35% |
| Nikitas Angelinas | 5 | 0.29% | 2 | 8.70% |
| Michael Christie | 4 | 0.24% | 1 | 4.35% |
| David Howells | 3 | 0.18% | 1 | 4.35% |
| Dmitriy Monakhov | 3 | 0.18% | 2 | 8.70% |
| Christoph Hellwig | 2 | 0.12% | 1 | 4.35% |
| Stephen Hemminger | 2 | 0.12% | 1 | 4.35% |
| Jakub Wilk | 2 | 0.12% | 1 | 4.35% |
| SF Markus Elfring | 1 | 0.06% | 1 | 4.35% |
| Greg Kroah-Hartman | 1 | 0.06% | 1 | 4.35% |
| Total | 1696 | 100.00% | 23 | 100.00% |
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