btrfs: Add btrfs_panic()
As part of the effort to eliminate BUG_ON as an error handling
technique, we need to determine which errors are actual logic errors,
which are on-disk corruption, and which are normal runtime errors
e.g. -ENOMEM.
Annotating these error cases is helpful to understand and report them.
This patch adds a btrfs_panic() routine that will either panic
or BUG depending on the new -ofatal_errors={panic,bug} mount option.
Since there are still so many BUG_ONs, it defaults to BUG for now but I
expect that to change once the error handling effort has made
significant progress.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 3ce97b2..9774e38 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -76,6 +76,9 @@
case -EROFS:
errstr = "Readonly filesystem";
break;
+ case -EEXIST:
+ errstr = "Object already exists";
+ break;
default:
if (nbuf) {
if (snprintf(nbuf, 16, "error %d", -errno) >= 0)
@@ -145,6 +148,36 @@
btrfs_handle_error(fs_info);
}
+/*
+ * __btrfs_panic decodes unexpected, fatal errors from the caller,
+ * issues an alert, and either panics or BUGs, depending on mount options.
+ */
+void __btrfs_panic(struct btrfs_fs_info *fs_info, const char *function,
+ unsigned int line, int errno, const char *fmt, ...)
+{
+ char nbuf[16];
+ char *s_id = "<unknown>";
+ const char *errstr;
+ struct va_format vaf = { .fmt = fmt };
+ va_list args;
+
+ if (fs_info)
+ s_id = fs_info->sb->s_id;
+
+ va_start(args, fmt);
+ vaf.va = &args;
+
+ errstr = btrfs_decode_error(fs_info, errno, nbuf);
+ if (fs_info->mount_opt & BTRFS_MOUNT_PANIC_ON_FATAL_ERROR)
+ panic(KERN_CRIT "BTRFS panic (device %s) in %s:%d: %pV (%s)\n",
+ s_id, function, line, &vaf, errstr);
+
+ printk(KERN_CRIT "BTRFS panic (device %s) in %s:%d: %pV (%s)\n",
+ s_id, function, line, &vaf, errstr);
+ va_end(args);
+ /* Caller calls BUG() */
+}
+
static void btrfs_put_super(struct super_block *sb)
{
(void)close_ctree(btrfs_sb(sb)->tree_root);
@@ -166,7 +199,7 @@
Opt_enospc_debug, Opt_subvolrootid, Opt_defrag, Opt_inode_cache,
Opt_no_space_cache, Opt_recovery, Opt_skip_balance,
Opt_check_integrity, Opt_check_integrity_including_extent_data,
- Opt_check_integrity_print_mask,
+ Opt_check_integrity_print_mask, Opt_fatal_errors,
Opt_err,
};
@@ -206,6 +239,7 @@
{Opt_check_integrity, "check_int"},
{Opt_check_integrity_including_extent_data, "check_int_data"},
{Opt_check_integrity_print_mask, "check_int_print_mask=%d"},
+ {Opt_fatal_errors, "fatal_errors=%s"},
{Opt_err, NULL},
};
@@ -438,6 +472,18 @@
ret = -EINVAL;
goto out;
#endif
+ case Opt_fatal_errors:
+ if (strcmp(args[0].from, "panic") == 0)
+ btrfs_set_opt(info->mount_opt,
+ PANIC_ON_FATAL_ERROR);
+ else if (strcmp(args[0].from, "bug") == 0)
+ btrfs_clear_opt(info->mount_opt,
+ PANIC_ON_FATAL_ERROR);
+ else {
+ ret = -EINVAL;
+ goto out;
+ }
+ break;
case Opt_err:
printk(KERN_INFO "btrfs: unrecognized mount option "
"'%s'\n", p);
@@ -766,6 +812,8 @@
seq_puts(seq, ",inode_cache");
if (btrfs_test_opt(root, SKIP_BALANCE))
seq_puts(seq, ",skip_balance");
+ if (btrfs_test_opt(root, PANIC_ON_FATAL_ERROR))
+ seq_puts(seq, ",fatal_errors=panic");
return 0;
}
