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authorMike Galbraith <mgalbraith@suse.de>2014-11-02 08:31:18 +0100
committerAnders Roxell <anders.roxell@linaro.org>2015-06-01 12:03:38 +0200
commit53be47e5c1fa3b4edce74a21771c6008163e91ab (patch)
tree29f6b52ab58defb1bb1843a516b7a6a2fb0ab896
parentbbfe357b1e0e63da5a2c97b154a2fd7ecc6d2c59 (diff)
downloadlinux-linaro-stable-53be47e5c1fa3b4edce74a21771c6008163e91ab.tar.gz
fs,btrfs: fix rt deadlock on extent_buffer->lock
Sat Jul 14 12:30:41 CEST 2012 Trivially repeatable deadlock is cured by enabling lockdep code in btrfs_clear_path_blocking() as suggested by Chris Mason. He also suggested restricting blocking reader count to one, and not allowing a spinning reader while blocking reader exists. This has proven to be unnecessary, the strict lock order enforcement is enough.. or rather that's my box's opinion after long hours of hard pounding. Note: extent-tree.c bit is additional recommendation from Chris Mason, split into a separate patch after discussion. Link: http://lkml.kernel.org/r/1414913478.5380.114.camel@marge.simpson.net Cc: linux-rt-users <linux-rt-users@vger.kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Carsten Emde <C.Emde@osadl.org> Cc: John Kacur <jkacur@redhat.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Clark Williams <williams@redhat.com> Cc: Chris Mason <chris.mason@fusionio.com> Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
-rw-r--r--fs/btrfs/ctree.c4
-rw-r--r--fs/btrfs/extent-tree.c8
2 files changed, 2 insertions, 10 deletions
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 93de3ba994e7..47bc9e613245 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -80,7 +80,7 @@ noinline void btrfs_clear_path_blocking(struct btrfs_path *p,
{
int i;
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
+#if (defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_PREEMPT_RT_BASE))
/* lockdep really cares that we take all of these spinlocks
* in the right order. If any of the locks in the path are not
* currently blocking, it is going to complain. So, make really
@@ -107,7 +107,7 @@ noinline void btrfs_clear_path_blocking(struct btrfs_path *p,
}
}
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
+#if (defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_PREEMPT_RT_BASE))
if (held)
btrfs_clear_lock_blocking_rw(held, held_rw);
#endif
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 794d7c6ea9ee..cb80d02edfa2 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -6939,14 +6939,6 @@ again:
goto again;
}
- if (btrfs_test_opt(root, ENOSPC_DEBUG)) {
- static DEFINE_RATELIMIT_STATE(_rs,
- DEFAULT_RATELIMIT_INTERVAL * 10,
- /*DEFAULT_RATELIMIT_BURST*/ 1);
- if (__ratelimit(&_rs))
- WARN(1, KERN_DEBUG
- "BTRFS: block rsv returned %d\n", ret);
- }
try_reserve:
ret = reserve_metadata_bytes(root, block_rsv, blocksize,
BTRFS_RESERVE_NO_FLUSH);