From 6dda9266913ad57e09afc1a10d6473f10c806a63 Mon Sep 17 00:00:00 2001 From: "Luck, Tony" Date: Thu, 11 Aug 2011 15:14:39 -0700 Subject: pstore: defer inserting OOPS entries into pstore Life is simple for all the kernel terminating types of kmsg_dump call backs - pstore just saves the tail end of the console log. But for "oops" the situation is more complex - the kernel may carry on running (possibly for ever). So we'd like to make the logged copy of the oops appear in the pstore filesystem - so that the user has a handle to clear the entry from the persistent backing store (if we don't, the store may fill with "oops" entries (that are also safely stashed in /var/log/messages) leaving no space for real errors. Current code calls pstore_mkfile() immediately. But this may not be safe. The oops could have happened with arbitrary locks held, or in interrupt or NMI context. So allocating memory and calling into generic filesystem code seems unwise. This patch defers making the entry appear. At the time of the oops, we merely set a flag "pstore_new_entry" noting that a new entry has been added. A periodic timer checks once a minute to see if the flag is set - if so, it schedules a work queue to rescan the backing store and make all new entries appear in the pstore filesystem. Signed-off-by: Tony Luck --- fs/pstore/inode.c | 40 ++++++++++++++++++++++++++++++++++---- fs/pstore/internal.h | 2 +- fs/pstore/platform.c | 54 +++++++++++++++++++++++++++++++++++++++++++--------- 3 files changed, 82 insertions(+), 14 deletions(-) (limited to 'fs/pstore') diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c index 893b961dcfd8..379a02dc1217 100644 --- a/fs/pstore/inode.c +++ b/fs/pstore/inode.c @@ -24,6 +24,7 @@ #include #include #include +#include #include #include #include @@ -32,13 +33,18 @@ #include #include #include +#include #include #include "internal.h" #define PSTORE_NAMELEN 64 +static DEFINE_SPINLOCK(allpstore_lock); +static LIST_HEAD(allpstore); + struct pstore_private { + struct list_head list; struct pstore_info *psi; enum pstore_type_id type; u64 id; @@ -81,8 +87,16 @@ static int pstore_unlink(struct inode *dir, struct dentry *dentry) static void pstore_evict_inode(struct inode *inode) { + struct pstore_private *p = inode->i_private; + unsigned long flags; + end_writeback(inode); - kfree(inode->i_private); + if (p) { + spin_lock_irqsave(&allpstore_lock, flags); + list_del(&p->list); + spin_unlock_irqrestore(&allpstore_lock, flags); + kfree(p); + } } static const struct inode_operations pstore_dir_inode_operations = { @@ -182,9 +196,23 @@ int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id, struct dentry *root = pstore_sb->s_root; struct dentry *dentry; struct inode *inode; - int rc; + int rc = 0; char name[PSTORE_NAMELEN]; - struct pstore_private *private; + struct pstore_private *private, *pos; + unsigned long flags; + + spin_lock_irqsave(&allpstore_lock, flags); + list_for_each_entry(pos, &allpstore, list) { + if (pos->type == type && + pos->id == id && + pos->psi == psi) { + rc = -EEXIST; + break; + } + } + spin_unlock_irqrestore(&allpstore_lock, flags); + if (rc) + return rc; rc = -ENOMEM; inode = pstore_get_inode(pstore_sb, root->d_inode, S_IFREG | 0444, 0); @@ -229,6 +257,10 @@ int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id, d_add(dentry, inode); + spin_lock_irqsave(&allpstore_lock, flags); + list_add(&private->list, &allpstore); + spin_unlock_irqrestore(&allpstore_lock, flags); + mutex_unlock(&root->d_inode->i_mutex); return 0; @@ -277,7 +309,7 @@ int pstore_fill_super(struct super_block *sb, void *data, int silent) goto fail; } - pstore_get_records(); + pstore_get_records(0); return 0; fail: diff --git a/fs/pstore/internal.h b/fs/pstore/internal.h index 611c1b3c46fa..3bde461c3f34 100644 --- a/fs/pstore/internal.h +++ b/fs/pstore/internal.h @@ -1,5 +1,5 @@ extern void pstore_set_kmsg_bytes(int); -extern void pstore_get_records(void); +extern void pstore_get_records(int); extern int pstore_mkfile(enum pstore_type_id, char *psname, u64 id, char *data, size_t size, struct timespec time, struct pstore_info *psi); diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c index c5300ec31696..ca60ebcfb15f 100644 --- a/fs/pstore/platform.c +++ b/fs/pstore/platform.c @@ -25,11 +25,28 @@ #include #include #include +#include #include #include +#include #include "internal.h" +/* + * We defer making "oops" entries appear in pstore - see + * whether the system is actually still running well enough + * to let someone see the entry + */ +#define PSTORE_INTERVAL (60 * HZ) + +static int pstore_new_entry; + +static void pstore_timefunc(unsigned long); +static DEFINE_TIMER(pstore_timer, pstore_timefunc, 0, 0); + +static void pstore_dowork(struct work_struct *); +static DECLARE_WORK(pstore_work, pstore_dowork); + /* * pstore_lock just protects "psinfo" during * calls to pstore_register() @@ -100,9 +117,7 @@ static void pstore_dump(struct kmsg_dumper *dumper, id = psinfo->write(PSTORE_TYPE_DMESG, part, hsize + l1_cpy + l2_cpy, psinfo); if (reason == KMSG_DUMP_OOPS && pstore_is_mounted()) - pstore_mkfile(PSTORE_TYPE_DMESG, psinfo->name, id, - psinfo->buf, hsize + l1_cpy + l2_cpy, - CURRENT_TIME, psinfo); + pstore_new_entry = 1; l1 -= l1_cpy; l2 -= l2_cpy; total += l1_cpy + l2_cpy; @@ -148,19 +163,24 @@ int pstore_register(struct pstore_info *psi) } if (pstore_is_mounted()) - pstore_get_records(); + pstore_get_records(0); kmsg_dump_register(&pstore_dumper); + pstore_timer.expires = jiffies + PSTORE_INTERVAL; + add_timer(&pstore_timer); + return 0; } EXPORT_SYMBOL_GPL(pstore_register); /* - * Read all the records from the persistent store. Create and - * file files in our filesystem. + * Read all the records from the persistent store. Create + * files in our filesystem. Don't warn about -EEXIST errors + * when we are re-scanning the backing store looking to add new + * error records. */ -void pstore_get_records(void) +void pstore_get_records(int quiet) { struct pstore_info *psi = psinfo; ssize_t size; @@ -178,8 +198,9 @@ void pstore_get_records(void) goto out; while ((size = psi->read(&id, &type, &time, psi)) > 0) { - if (pstore_mkfile(type, psi->name, id, psi->buf, (size_t)size, - time, psi)) + rc = pstore_mkfile(type, psi->name, id, psi->buf, (size_t)size, + time, psi); + if (rc && (rc != -EEXIST || !quiet)) failed++; } psi->close(psi); @@ -191,6 +212,21 @@ out: failed, psi->name); } +static void pstore_dowork(struct work_struct *work) +{ + pstore_get_records(1); +} + +static void pstore_timefunc(unsigned long dummy) +{ + if (pstore_new_entry) { + pstore_new_entry = 0; + schedule_work(&pstore_work); + } + + mod_timer(&pstore_timer, jiffies + PSTORE_INTERVAL); +} + /* * Call platform driver to write a record to the * persistent store. -- cgit v1.2.1