From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 20:49:45 +0200 Subject: Adding upstream version 6.1.76. Signed-off-by: Daniel Baumann --- fs/ext4/mmp.c | 414 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 414 insertions(+) create mode 100644 fs/ext4/mmp.c (limited to 'fs/ext4/mmp.c') diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c new file mode 100644 index 000000000..24b3bedda --- /dev/null +++ b/fs/ext4/mmp.c @@ -0,0 +1,414 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include + +#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); +} + +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); +} + +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); +} + +/* + * Write the MMP block using REQ_SYNC to try to get the block on-disk + * faster. + */ +static int write_mmp_block_thawed(struct super_block *sb, + struct buffer_head *bh) +{ + struct mmp_struct *mmp = (struct mmp_struct *)(bh->b_data); + + ext4_mmp_csum_set(sb, mmp); + 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); + if (unlikely(!buffer_uptodate(bh))) + return -EIO; + return 0; +} + +static int write_mmp_block(struct super_block *sb, struct buffer_head *bh) +{ + int err; + + /* + * We protect against freezing so that we don't create dirty buffers + * on frozen filesystem. + */ + sb_start_write(sb); + err = write_mmp_block_thawed(sb, bh); + sb_end_write(sb); + return err; +} + +/* + * 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; + } + } + + lock_buffer(*bh); + ret = ext4_read_bh(*bh, REQ_META | REQ_PRIO, NULL); + if (ret) + 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; +} + +/* + * 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", + (unsigned long long)le64_to_cpu(mmp->mmp_time), + (int)sizeof(mmp->mmp_nodename), mmp->mmp_nodename, + (int)sizeof(mmp->mmp_bdevname), mmp->mmp_bdevname); +} + +/* + * kmmpd will update the MMP sequence every s_mmp_update_interval seconds + */ +static int kmmpd(void *data) +{ + struct super_block *sb = data; + struct ext4_super_block *es = EXT4_SB(sb)->s_es; + struct buffer_head *bh = EXT4_SB(sb)->s_mmp_bh; + 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 = 0; + + mmp_block = le64_to_cpu(es->s_mmp_block); + mmp = (struct mmp_struct *)(bh->b_data); + mmp->mmp_time = cpu_to_le64(ktime_get_real_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); + + memcpy(mmp->mmp_nodename, init_utsname()->nodename, + sizeof(mmp->mmp_nodename)); + + while (!kthread_should_stop() && !sb_rdonly(sb)) { + if (!ext4_has_feature_mmp(sb)) { + ext4_warning(sb, "kmmpd being stopped since MMP feature" + " has been disabled."); + goto wait_to_exit; + } + if (++seq > EXT4_MMP_SEQ_MAX) + seq = 1; + + mmp->mmp_seq = cpu_to_le32(seq); + mmp->mmp_time = cpu_to_le64(ktime_get_real_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_err(sb, -retval, + "Error writing to MMP block"); + } + failed_writes++; + } + + 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_err(sb, -retval, + "error reading MMP data: %d", + retval); + goto wait_to_exit; + } + + 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_err(sb, EBUSY, "abort"); + put_bh(bh_check); + retval = -EBUSY; + goto wait_to_exit; + } + 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(ktime_get_real_seconds()); + + retval = write_mmp_block(sb, bh); + +wait_to_exit: + while (!kthread_should_stop()) { + set_current_state(TASK_INTERRUPTIBLE); + if (!kthread_should_stop()) + schedule(); + } + set_current_state(TASK_RUNNING); + return retval; +} + +void ext4_stop_mmpd(struct ext4_sb_info *sbi) +{ + if (sbi->s_mmp_tsk) { + kthread_stop(sbi->s_mmp_tsk); + brelse(sbi->s_mmp_bh); + sbi->s_mmp_tsk = NULL; + } +} + +/* + * 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 = get_random_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; + 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"); + retval = -EINVAL; + 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"); + retval = -EBUSY; + 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"); + retval = -ETIMEDOUT; + 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."); + retval = -EBUSY; + goto failed; + } + +skip: + /* + * write a new random sequence number. + */ + seq = mmp_new_seq(); + mmp->mmp_seq = cpu_to_le32(seq); + + /* + * On mount / remount we are protected against fs freezing (by s_umount + * semaphore) and grabbing freeze protection upsets lockdep + */ + retval = write_mmp_block_thawed(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"); + retval = -ETIMEDOUT; + 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."); + retval = -EBUSY; + goto failed; + } + + EXT4_SB(sb)->s_mmp_bh = bh; + + BUILD_BUG_ON(sizeof(mmp->mmp_bdevname) < BDEVNAME_SIZE); + snprintf(mmp->mmp_bdevname, sizeof(mmp->mmp_bdevname), + "%pg", bh->b_bdev); + + /* + * Start a kernel thread to update the MMP block periodically. + */ + EXT4_SB(sb)->s_mmp_tsk = kthread_run(kmmpd, sb, "kmmpd-%.*s", + (int)sizeof(mmp->mmp_bdevname), + mmp->mmp_bdevname); + if (IS_ERR(EXT4_SB(sb)->s_mmp_tsk)) { + EXT4_SB(sb)->s_mmp_tsk = NULL; + ext4_warning(sb, "Unable to create kmmpd thread for %s.", + sb->s_id); + retval = -ENOMEM; + goto failed; + } + + return 0; + +failed: + brelse(bh); + return retval; +} -- cgit v1.2.3