[PATCH 3/4] printk/btrfs: Handle more message headers

From: Petr Mladek
Date: Thu Oct 27 2016 - 11:53:35 EST


The commit 4bcc595ccd80decb4245096e ("printk: reinstate KERN_CONT for
printing continuation lines") allows to define more message headers
for a single message. The motivation is that continuous lines might
get mixed. Therefore it make sense to define the right log level
for every piece of a cont line.

The current btrfs_printk() macros do not support continuous lines
at the moment. But better be prepared for a custom messages and
avoid potential "lvl" buffer overflow.

This patch iterates over the entire message header. It is interested
only into the message level like the original code.

Note that 3 bytes should be enough for the header buffer. I am not
sure where the 4 bytes came from. Maybe it expected that both
KERN_SOH and the log level strings end with '\0' but they
are concatenated.

Also I fixed the default ratelimit level. It looked very strange
when it was different from the default log level.

Signed-off-by: Petr Mladek <pmladek@xxxxxxxx>
---
fs/btrfs/super.c | 28 +++++++++++++++-------------
1 file changed, 15 insertions(+), 13 deletions(-)

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 74ed5aae6cea..2d836c676895 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -202,27 +202,29 @@ void __btrfs_handle_fs_error(struct btrfs_fs_info *fs_info, const char *function
void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...)
{
struct super_block *sb = fs_info->sb;
- char lvl[4];
+ char lvl[3];
struct va_format vaf;
va_list args;
- const char *type = logtypes[4];
+ const char *type = NULL;
int kern_level;
struct ratelimit_state *ratelimit;

va_start(args, fmt);

- kern_level = printk_get_level(fmt);
- if (kern_level) {
- size_t size = printk_skip_level(fmt) - fmt;
- memcpy(lvl, fmt, size);
- lvl[size] = '\0';
- fmt += size;
- type = logtypes[kern_level - '0'];
- ratelimit = &printk_limits[kern_level - '0'];
- } else {
+ while ((kern_level = printk_get_level(fmt)) != 0) {
+ if (kern_level >= '0' || kern_level <= '7') {
+ memcpy(lvl, fmt, 2);
+ lvl[2] = '\0';
+ type = logtypes[kern_level - '0'];
+ ratelimit = &printk_limits[kern_level - '0'];
+ }
+ fmt += 2;
+ }
+
+ if (!type) {
*lvl = '\0';
- /* Default to debug output */
- ratelimit = &printk_limits[7];
+ type = logtypes[4];
+ ratelimit = &printk_limits[4];
}

vaf.fmt = fmt;
--
1.8.5.6