cregit-Linux how code gets into the kernel

Release 4.10 fs/ext4/mmp.c

Directory: fs/ext4
#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); }


darrick j. wongdarrick j. wong6498.46%150.00%
dmitriy monakhovdmitriy monakhov11.54%150.00%

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); }


darrick j. wongdarrick j. wong3794.87%133.33%
dmitriy monakhovdmitriy monakhov12.56%133.33%
stephen hemmingerstephen hemminger12.56%133.33%

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); }


darrick j. wongdarrick j. wong3494.44%133.33%
dmitriy monakhovdmitriy monakhov12.78%133.33%
stephen hemmingerstephen hemminger12.78%133.33%

/* * 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; }


johann lombardijohann lombardi6056.60%116.67%
darrick j. wongdarrick j. wong2826.42%116.67%
jan karajan kara1110.38%116.67%
theodore tsotheodore tso43.77%116.67%
michael christiemichael christie21.89%116.67%
christoph hellwigchristoph hellwig10.94%116.67%

/* * 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; }


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dan carpenterdan carpenter3616.44%112.50%
vikram jadhav07 at gmail.comvikram jadhav07 at gmail.com219.59%112.50%
darrick j. wongdarrick j. wong209.13%225.00%
theodore tsotheodore tso94.11%225.00%
michael christiemichael christie20.91%112.50%

/* * 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); }


johann lombardijohann lombardi7296.00%133.33%
dan carpenterdan carpenter22.67%133.33%
jakub wilkjakub wilk11.33%133.33%

/* * 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->s_flags & MS_RDONLY) { 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; }


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vikram jadhav07 at gmail.comvikram jadhav07 at gmail.com244.38%120.00%
nikitas angelinasnikitas angelinas50.91%240.00%
darrick j. wongdarrick j. wong40.73%120.00%

/* * 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; }


johann lombardijohann lombardi2790.00%150.00%
theodore tsotheodore tso310.00%150.00%

/* * 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(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; }


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darrick j. wongdarrick j. wong81.45%240.00%
santosh nayaksantosh nayak61.08%120.00%
jakub wilkjakub wilk10.18%120.00%

Overall Contributors

johann lombardijohann lombardi136680.54%15.00%
darrick j. wongdarrick j. wong19611.56%315.00%
vikram jadhav07 at gmail.comvikram jadhav07 at gmail.com452.65%15.00%
dan carpenterdan carpenter382.24%210.00%
theodore tsotheodore tso160.94%315.00%
jan karajan kara110.65%15.00%
santosh nayaksantosh nayak60.35%15.00%
nikitas angelinasnikitas angelinas50.29%210.00%
michael christiemichael christie40.24%15.00%
dmitriy monakhovdmitriy monakhov30.18%210.00%
christoph hellwigchristoph hellwig20.12%15.00%
jakub wilkjakub wilk20.12%15.00%
stephen hemmingerstephen hemminger20.12%15.00%
Directory: fs/ext4
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