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jbd2: use a single printk for jbd_debug() 

Since the jbd_debug() is implemented with two separate printk()
calls, it can lead to corrupted and misleading debug output like
the following (see lines marked with "*"):

[  290.339362] (fs/jbd2/journal.c, 203): kjournald2: kjournald2 wakes
[  290.339365] (fs/jbd2/journal.c, 155): kjournald2: commit_sequence=42103, commit_request=42104
[  290.339369] (fs/jbd2/journal.c, 158): kjournald2: OK, requests differ
[* 290.339376] (fs/jbd2/journal.c, 648): jbd2_log_wait_commit:
[* 290.339379] (fs/jbd2/commit.c, 370): jbd2_journal_commit_transaction: JBD2: want 42104, j_commit_sequence=42103
[* 290.339382] JBD2: starting commit of transaction 42104
[  290.339410] (fs/jbd2/revoke.c, 566): jbd2_journal_write_revoke_records: Wrote 0 revoke records
[  290.376555] (fs/jbd2/commit.c, 1088): jbd2_journal_commit_transaction: JBD2: commit 42104 complete, head 42079

i.e. the debug output from log_wait_commit and journal_commit_transaction
have become interleaved.  The output should have been:

(fs/jbd2/journal.c, 648): jbd2_log_wait_commit: JBD2: want 42104, j_commit_sequence=42103
(fs/jbd2/commit.c, 370): jbd2_journal_commit_transaction: JBD2: starting commit of transaction 42104

It is expected that this is not easy to replicate -- I was only able
to cause it on preempt-rt kernels, and even then only under heavy
I/O load.

Reported-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Suggested-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Paul Gortmaker 2013-06-12 23:04:04 -04:00 committed by Theodore Ts'o
parent c9b3a8ccb7
commit 169f1a2a87
2 changed files with 23 additions and 9 deletions
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18
fs/jbd2/journal.c
View File

@ -103,6 +103,24 @@ EXPORT_SYMBOL(jbd2_inode_cache);
static void __journal_abort_soft (journal_t *journal, int errno);
static int jbd2_journal_create_slab(size_t slab_size);
#ifdef CONFIG_JBD2_DEBUG
void __jbd2_debug(int level, const char *file, const char *func,
unsigned int line, const char *fmt, ...)
{
struct va_format vaf;
va_list args;
if (level > jbd2_journal_enable_debug)
return;
va_start(args, fmt);
vaf.fmt = fmt;
vaf.va = &args;
printk(KERN_DEBUG "%s: (%s, %u): %pV\n", file, func, line, &vaf);
va_end(args);
}
EXPORT_SYMBOL(__jbd2_debug);
#endif
/* Checksumming functions */
int jbd2_verify_csum_type(journal_t *j, journal_superblock_t *sb)
{

14
include/linux/jbd2.h
View File

@ -56,17 +56,13 @@
*/
#define JBD2_EXPENSIVE_CHECKING
extern ushort jbd2_journal_enable_debug;
void __jbd2_debug(int level, const char *file, const char *func,
unsigned int line, const char *fmt, ...);
#define jbd_debug(n, f, a...) \
do { \
if ((n) <= jbd2_journal_enable_debug) { \
printk (KERN_DEBUG "(%s, %d): %s: ", \
__FILE__, __LINE__, __func__); \
printk (f, ## a); \
} \
} while (0)
#define jbd_debug(n, fmt, a...) \
__jbd2_debug((n), __FILE__, __func__, __LINE__, (fmt), ##a)
#else
#define jbd_debug(f, a...) /**/
#define jbd_debug(n, fmt, a...) /**/
#endif
extern void *jbd2_alloc(size_t size, gfp_t flags);