From 3942ae5319640ced5844b75f44884e4bcb8a2f16 Mon Sep 17 00:00:00 2001 From: Steven Whitehouse Date: Mon, 11 Jul 2011 08:53:30 +0100 Subject: [PATCH] GFS2: Fix race during filesystem mount There is a potential race during filesystem mounting which has recently been reported. It occurs when the userland gfs_controld is able to process requests fast enough that it tries to use the sysfs interface before the lock module is properly initialised. This is a pretty unusual case as normally the lock module initialisation is very quick compared with gfs_controld. This patch adds an interruptible completion which is used to ensure that userland will wait for the initialisation of the lock module to complete. There are other potential solutions to this problem, but this is the quickest at this stage and has been tested both with and without mount.gfs2 present in the system. Signed-off-by: Steven Whitehouse Reported-by: David Booher --- fs/gfs2/incore.h | 2 ++ fs/gfs2/ops_fstype.c | 3 +++ fs/gfs2/sys.c | 7 ++++++- 3 files changed, 11 insertions(+), 1 deletion(-) diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h index 0a064e91ac70..81206e70cbf6 100644 --- a/fs/gfs2/incore.h +++ b/fs/gfs2/incore.h @@ -17,6 +17,7 @@ #include #include #include +#include #define DIO_WAIT 0x00000010 #define DIO_METADATA 0x00000020 @@ -546,6 +547,7 @@ struct gfs2_sbd { struct gfs2_glock *sd_trans_gl; wait_queue_head_t sd_glock_wait; atomic_t sd_glock_disposal; + struct completion sd_locking_init; /* Inode Stuff */ diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c index 8ac9ae189b53..2a77071fb7b6 100644 --- a/fs/gfs2/ops_fstype.c +++ b/fs/gfs2/ops_fstype.c @@ -72,6 +72,7 @@ static struct gfs2_sbd *init_sbd(struct super_block *sb) init_waitqueue_head(&sdp->sd_glock_wait); atomic_set(&sdp->sd_glock_disposal, 0); + init_completion(&sdp->sd_locking_init); spin_lock_init(&sdp->sd_statfs_spin); spin_lock_init(&sdp->sd_rindex_spin); @@ -1017,11 +1018,13 @@ hostdata_error: fsname++; if (lm->lm_mount == NULL) { fs_info(sdp, "Now mounting FS...\n"); + complete(&sdp->sd_locking_init); return 0; } ret = lm->lm_mount(sdp, fsname); if (ret == 0) fs_info(sdp, "Joined cluster. Now mounting FS...\n"); + complete(&sdp->sd_locking_init); return ret; } diff --git a/fs/gfs2/sys.c b/fs/gfs2/sys.c index e20eab37bc80..443cabcfcd23 100644 --- a/fs/gfs2/sys.c +++ b/fs/gfs2/sys.c @@ -338,6 +338,9 @@ static ssize_t lkfirst_store(struct gfs2_sbd *sdp, const char *buf, size_t len) rv = sscanf(buf, "%u", &first); if (rv != 1 || first > 1) return -EINVAL; + rv = wait_for_completion_killable(&sdp->sd_locking_init); + if (rv) + return rv; spin_lock(&sdp->sd_jindex_spin); rv = -EBUSY; if (test_bit(SDF_NOJOURNALID, &sdp->sd_flags) == 0) @@ -414,7 +417,9 @@ static ssize_t jid_store(struct gfs2_sbd *sdp, const char *buf, size_t len) rv = sscanf(buf, "%d", &jid); if (rv != 1) return -EINVAL; - + rv = wait_for_completion_killable(&sdp->sd_locking_init); + if (rv) + return rv; spin_lock(&sdp->sd_jindex_spin); rv = -EINVAL; if (sdp->sd_lockstruct.ls_ops->lm_mount == NULL) -- 2.20.1