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 <je...@suse.com>
---
fs/btrfs/ctree.h | 11 +++++++++++
fs/btrfs/super.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 60 insertions(+), 1 deletion(-)
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1363,6 +1363,7 @@ struct btrfs_ioctl_defrag_range_args {
#define BTRFS_MOUNT_ENOSPC_DEBUG (1 << 15)
#define BTRFS_MOUNT_AUTO_DEFRAG (1 << 16)
#define BTRFS_MOUNT_INODE_MAP_CACHE (1 << 17)
+#define BTRFS_MOUNT_PANIC_ON_FATAL_ERROR (1 << 18)
#define btrfs_clear_opt(o, opt) ((o) &= ~BTRFS_MOUNT_##opt)
#define btrfs_set_opt(o, opt) ((o) |= BTRFS_MOUNT_##opt)
@@ -2648,6 +2649,16 @@ do {
\
__btrfs_std_error((fs_info), __func__, __LINE__, (errno));\
} while (0)
+void __btrfs_panic(struct btrfs_fs_info *fs_info, const char *function,
+ unsigned int line, int errno, const char *fmt, ...);
+
+#define btrfs_panic(fs_info, errno, fmt, args...) \
+do { \
+ struct btrfs_fs_info *_i = (fs_info); \
+ __btrfs_panic(_i, __func__, __LINE__, errno, fmt, ##args); \
+ BUG_ON(!(_i->mount_opt & BTRFS_MOUNT_PANIC_ON_FATAL_ERROR)); \
+} while (0)
+
/* acl.c */
#ifdef CONFIG_BTRFS_FS_POSIX_ACL
struct posix_acl *btrfs_get_acl(struct inode *inode, int type);
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -74,6 +74,9 @@ static const char *btrfs_decode_error(st
case -EROFS:
errstr = "Readonly filesystem";
break;
+ case -EEXIST:
+ errstr = "Object already exists";
+ break;
default:
if (nbuf) {
if (snprintf(nbuf, 16, "error %d", -errno) >= 0)
@@ -143,6 +146,36 @@ void __btrfs_std_error(struct btrfs_fs_i
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)
{
struct btrfs_root *root = btrfs_sb(sb);
@@ -162,7 +195,7 @@ enum {
Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_discard,
Opt_space_cache, Opt_clear_cache, Opt_user_subvol_rm_allowed,
Opt_enospc_debug, Opt_subvolrootid, Opt_defrag,
- Opt_inode_cache, Opt_err,
+ Opt_inode_cache, Opt_fatal_errors, Opt_err,
};
static match_table_t tokens = {
@@ -195,6 +228,7 @@ static match_table_t tokens = {
{Opt_subvolrootid, "subvolrootid=%d"},
{Opt_defrag, "autodefrag"},
{Opt_inode_cache, "inode_cache"},
+ {Opt_fatal_errors, "fatal_errors=%s"},
{Opt_err, NULL},
};
@@ -381,6 +415,18 @@ int btrfs_parse_options(struct btrfs_roo
printk(KERN_INFO "btrfs: enabling auto defrag");
btrfs_set_opt(info->mount_opt, AUTO_DEFRAG);
break;
+ 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);
@@ -729,6 +775,8 @@ static int btrfs_show_options(struct seq
seq_puts(seq, ",autodefrag");
if (btrfs_test_opt(root, INODE_MAP_CACHE))
seq_puts(seq, ",inode_cache");
+ if (btrfs_test_opt(root, PANIC_ON_FATAL_ERROR))
+ seq_puts(seq, ",fatal_errors=panic");
return 0;
}
--
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