linux-ext4 - [PATCH] jbd2: Create proc entry with bdevname+i

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Message-ID: <20080908233114.GD20100@mail.oracle.com>
Date:	Mon, 8 Sep 2008 16:31:14 -0700
From:	Joel Becker <Joel.Becker@...cle.com>
To:	"linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>
Cc:	ocfs2-devel@....oracle.com, mfasheh@...e.com,
	sunil.mushran@...cle.com
Subject: [PATCH] jbd2: Create proc entry with bdevname+i_ino.

jbd2 currently creates statistics files for each loaded journal in
/proc/fs/jbd2/<bdevname>.  ocfs2 loads multiple journals when recovering
other nodes, and the multiple journals on a given bdev collide in the
proc namespace.

This patch changes the location to /proc/fs/jbd2/<bdevname>-<i_ino> as
proposed by Jan Kara.  ocfs2 can load multiple journals safely without
collision.  There are, to my knowledge, no programmatic users, so the
name change shouldn't (haha) cause any problems.

ocfs2 has 64bit inode numbers, so a collision could theoretically happen
with inodes above 32bits, but ocfs2 journals are generally created at
the front of the volume during mkfs(8).  In addition, ocfs2 restricts
inodes to 32bits unless the 'inode64' option is specified.

Signed-off-by: Joel Becker <joel.becker@...cle.com>
---
 fs/jbd2/journal.c |   12 ++++++++----
 1 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 8207a01..18d3063 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -901,9 +901,11 @@ static struct proc_dir_entry *proc_jbd2_stats;
 
 static void jbd2_stats_proc_init(journal_t *journal)
 {
-	char name[BDEVNAME_SIZE];
+	char dname[BDEVNAME_SIZE];
+	char name[NAME_MAX];
 
-	bdevname(journal->j_dev, name);
+	bdevname(journal->j_dev, dname);
+	snprintf(name, NAME_MAX, "%s-%lu", dname, journal->j_inode->i_ino);
 	journal->j_proc_entry = proc_mkdir(name, proc_jbd2_stats);
 	if (journal->j_proc_entry) {
 		proc_create_data("history", S_IRUGO, journal->j_proc_entry,
@@ -915,9 +917,11 @@ static void jbd2_stats_proc_init(journal_t *journal)
 
 static void jbd2_stats_proc_exit(journal_t *journal)
 {
-	char name[BDEVNAME_SIZE];
+	char dname[BDEVNAME_SIZE];
+	char name[NAME_MAX];
 
-	bdevname(journal->j_dev, name);
+	bdevname(journal->j_dev, dname);
+	snprintf(name, NAME_MAX, "%s-%lu", dname, journal->j_inode->i_ino);
 	remove_proc_entry("info", journal->j_proc_entry);
 	remove_proc_entry("history", journal->j_proc_entry);
 	remove_proc_entry(name, proc_jbd2_stats);
-- 
1.5.6.3


-- 

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Joel Becker
Principal Software Developer
Oracle
E-mail: joel.becker@...cle.com
Phone: (650) 506-8127
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