Currently most of the messages btrfs produce are not rate limited.
Recently I came accross a case where due to FS corruption an excessive
amount of printk caused the softlockup detector to trigger and reset
the server. This patch does the following changes:
* The message which was printed is converted to use the ratelimited
version of btrfs_info function. This will prevent it from exploding
in the future.
* In addition to the above change, also add a sort of a "safet net" to
all non-ratelimited prints by introducing separate ratelimiting for
every message class when the "naked" btrfs_info is called.
Signed-off-by: Nikolay Borisov <kernel@xxxxxxxx>
---
Hello David,
How about something like that?
fs/btrfs/file-item.c | 2 +-
fs/btrfs/super.c | 21 +++++++++++++++++++--
2 files changed, 20 insertions(+), 3 deletions(-)
diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 62a81ee13a5f..6b58d0620e2f 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -250,7 +250,7 @@ static int __btrfs_lookup_bio_sums(struct btrfs_root *root,
offset + root->sectorsize - 1,
EXTENT_NODATASUM);
} else {
- btrfs_info(BTRFS_I(inode)->root->fs_info,
+ btrfs_info_rl(BTRFS_I(inode)->root->fs_info,
"no csum found for inode %llu start %llu",
btrfs_ino(inode), offset);
}
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 60e7179ed4b7..01a87dd89732 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -184,6 +184,17 @@ static const char * const logtypes[] = {
"debug",
};
+static struct ratelimit_state printk_limits[] = {
+ RATELIMIT_STATE_INIT(printk_limits[0], DEFAULT_RATELIMIT_INTERVAL, 100),
+ RATELIMIT_STATE_INIT(printk_limits[1], DEFAULT_RATELIMIT_INTERVAL, 100),
+ RATELIMIT_STATE_INIT(printk_limits[2], DEFAULT_RATELIMIT_INTERVAL, 100),
+ RATELIMIT_STATE_INIT(printk_limits[3], DEFAULT_RATELIMIT_INTERVAL, 100),
+ RATELIMIT_STATE_INIT(printk_limits[4], DEFAULT_RATELIMIT_INTERVAL, 100),
+ RATELIMIT_STATE_INIT(printk_limits[5], DEFAULT_RATELIMIT_INTERVAL, 100),
+ RATELIMIT_STATE_INIT(printk_limits[6], DEFAULT_RATELIMIT_INTERVAL, 100),
+ RATELIMIT_STATE_INIT(printk_limits[7], DEFAULT_RATELIMIT_INTERVAL, 100),
+};
+
void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...)
{
struct super_block *sb = fs_info->sb;
@@ -192,6 +203,7 @@ void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...)
va_list args;
const char *type = logtypes[4];
int kern_level;
+ struct ratelimit_state *ratelimit;
va_start(args, fmt);
@@ -202,13 +214,18 @@ void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...)
lvl[size] = '\0';
fmt += size;
type = logtypes[kern_level - '0'];
- } else
+ ratelimit = &printk_limits[kern_level - '0'];
+ } else {
*lvl = '\0';
+ /* Default to debug output */
+ ratelimit = &printk_limits[7];
+ }
vaf.fmt = fmt;
vaf.va = &args;
- printk("%sBTRFS %s (device %s): %pV\n", lvl, type, sb->s_id, &vaf);
+ if (__ratelimit(ratelimit))
+ printk("%sBTRFS %s (device %s): %pV\n", lvl, type, sb->s_id, &vaf);
va_end(args);
}
--
2.5.0
--
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