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Message-ID: <1375383668-8072-5-git-send-email-paul.gortmaker@windriver.com> Date: Thu, 1 Aug 2013 15:01:08 -0400 From: Paul Gortmaker <paul.gortmaker@...driver.com> To: Jan Kara <jack@...e.cz> CC: Andrew Morton <akpm@...ux-foundation.org>, <linux-ext4@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Paul Gortmaker <paul.gortmaker@...driver.com> Subject: [PATCH 4/4] jbd: use a single printk for jbd_debug() Backport of jbd2 commit 169f1a2a87aae44034da4b9f81be1683d33de6d0 ("jbd2: use a single printk for jbd_debug()") Quoting the original: -------------- 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. -------------- Signed-off-by: Paul Gortmaker <paul.gortmaker@...driver.com> --- fs/jbd/journal.c | 18 ++++++++++++++++++ include/linux/jbd.h | 15 ++++++--------- 2 files changed, 24 insertions(+), 9 deletions(-) diff --git a/fs/jbd/journal.c b/fs/jbd/journal.c index 166263d..f45f0a3 100644 --- a/fs/jbd/journal.c +++ b/fs/jbd/journal.c @@ -97,6 +97,24 @@ static int journal_convert_superblock_v1(journal_t *, journal_superblock_t *); static void __journal_abort_soft (journal_t *journal, int errno); static const char *journal_dev_name(journal_t *journal, char *buffer); +#ifdef CONFIG_JBD_DEBUG +void __jbd_debug(int level, const char *file, const char *func, + unsigned int line, const char *fmt, ...) +{ + struct va_format vaf; + va_list args; + + if (level > jbd_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(__jbd_debug); +#endif + /* * Helper function used to manage commit timeouts */ diff --git a/include/linux/jbd.h b/include/linux/jbd.h index e45b430..d6d3ae0 100644 --- a/include/linux/jbd.h +++ b/include/linux/jbd.h @@ -56,16 +56,13 @@ #define JBD_EXPENSIVE_CHECKING extern ushort journal_enable_debug; -#define jbd_debug(n, f, a...) \ - do { \ - if ((n) <= journal_enable_debug) { \ - printk (KERN_DEBUG "(%s, %d): %s: ", \ - __FILE__, __LINE__, __func__); \ - printk (f, ## a); \ - } \ - } while (0) +void __jbd_debug(int level, const char *file, const char *func, + unsigned int line, const char *fmt, ...); + +#define jbd_debug(n, fmt, a...) \ + __jbd_debug((n), __FILE__, __func__, __LINE__, (fmt), ##a) #else -#define jbd_debug(f, a...) /**/ +#define jbd_debug(n, fmt, a...) /**/ #endif static inline void *jbd_alloc(size_t size, gfp_t flags) -- 1.8.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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