diff options
| -rw-r--r-- | Documentation/sysrq.txt | 5 | ||||
| -rw-r--r-- | drivers/char/sysrq.c | 19 | ||||
| -rw-r--r-- | fs/buffer.c | 33 | ||||
| -rw-r--r-- | include/linux/fs.h | 1 |
4 files changed, 57 insertions, 1 deletions
diff --git a/Documentation/sysrq.txt b/Documentation/sysrq.txt index 9e592c718af..afa2946892d 100644 --- a/Documentation/sysrq.txt +++ b/Documentation/sysrq.txt @@ -81,6 +81,8 @@ On all - write a character to /proc/sysrq-trigger. e.g.: 'i' - Send a SIGKILL to all processes, except for init. +'j' - Forcibly "Just thaw it" - filesystems frozen by the FIFREEZE ioctl. + 'k' - Secure Access Key (SAK) Kills all programs on the current virtual console. NOTE: See important comments below in SAK section. @@ -160,6 +162,9 @@ t'E'rm and k'I'll are useful if you have some sort of runaway process you are unable to kill any other way, especially if it's spawning other processes. +"'J'ust thaw it" is useful if your system becomes unresponsive due to a frozen +(probably root) filesystem via the FIFREEZE ioctl. + * Sometimes SysRq seems to get 'stuck' after using it, what can I do? ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ That happens to me, also. I've found that tapping shift, alt, and control diff --git a/drivers/char/sysrq.c b/drivers/char/sysrq.c index 33a9351c896..5afe7316c72 100644 --- a/drivers/char/sysrq.c +++ b/drivers/char/sysrq.c @@ -346,6 +346,19 @@ static struct sysrq_key_op sysrq_moom_op = { .enable_mask = SYSRQ_ENABLE_SIGNAL, }; +#ifdef CONFIG_BLOCK +static void sysrq_handle_thaw(int key, struct tty_struct *tty) +{ + emergency_thaw_all(); +} +static struct sysrq_key_op sysrq_thaw_op = { + .handler = sysrq_handle_thaw, + .help_msg = "thaw-filesystems(J)", + .action_msg = "Emergency Thaw of all frozen filesystems", + .enable_mask = SYSRQ_ENABLE_SIGNAL, +}; +#endif + static void sysrq_handle_kill(int key, struct tty_struct *tty) { send_sig_all(SIGKILL); @@ -396,9 +409,13 @@ static struct sysrq_key_op *sysrq_key_table[36] = { &sysrq_moom_op, /* f */ /* g: May be registered by ppc for kgdb */ NULL, /* g */ - NULL, /* h */ + NULL, /* h - reserved for help */ &sysrq_kill_op, /* i */ +#ifdef CONFIG_BLOCK + &sysrq_thaw_op, /* j */ +#else NULL, /* j */ +#endif &sysrq_SAK_op, /* k */ #ifdef CONFIG_SMP &sysrq_showallcpus_op, /* l */ diff --git a/fs/buffer.c b/fs/buffer.c index c77b848c3d4..f5f8b15a6e4 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -547,6 +547,39 @@ repeat: return err; } +void do_thaw_all(unsigned long unused) +{ + struct super_block *sb; + char b[BDEVNAME_SIZE]; + + spin_lock(&sb_lock); +restart: + list_for_each_entry(sb, &super_blocks, s_list) { + sb->s_count++; + spin_unlock(&sb_lock); + down_read(&sb->s_umount); + while (sb->s_bdev && !thaw_bdev(sb->s_bdev, sb)) + printk(KERN_WARNING "Emergency Thaw on %s\n", + bdevname(sb->s_bdev, b)); + up_read(&sb->s_umount); + spin_lock(&sb_lock); + if (__put_super_and_need_restart(sb)) + goto restart; + } + spin_unlock(&sb_lock); + printk(KERN_WARNING "Emergency Thaw complete\n"); +} + +/** + * emergency_thaw_all -- forcibly thaw every frozen filesystem + * + * Used for emergency unfreeze of all filesystems via SysRq + */ +void emergency_thaw_all(void) +{ + pdflush_operation(do_thaw_all, 0); +} + /** * sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers * @mapping: the mapping which wants those buffers written diff --git a/include/linux/fs.h b/include/linux/fs.h index 87e7bfc5ebd..61211ad823f 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1878,6 +1878,7 @@ extern struct block_device *open_by_devnum(dev_t, fmode_t); extern void invalidate_bdev(struct block_device *); extern int sync_blockdev(struct block_device *bdev); extern struct super_block *freeze_bdev(struct block_device *); +extern void emergency_thaw_all(void); extern int thaw_bdev(struct block_device *bdev, struct super_block *sb); extern int fsync_bdev(struct block_device *); extern int fsync_super(struct super_block *); |