Re: [f2fs-dev] assertion failed
Hi, Thank you for the report. Could you share the kernel and f2fs-tools versions? Let me check. Thank you, 2014-03-23 23:22 GMT+09:00 folkert folk...@vanheusden.com: Hi, Got an assertion failed in fsck.f2fs: Info: sector size = 512 Info: total sectors = 7503872 (in 512bytes) Assertion failed! [fsck_chk_node_blk: 209] nid == le32_to_cpu(node_blk-footer.nid) -- nid[0x5] blk_addr[0xc1d35] footer.nid[0x0] Folkert van Heusden -- Multi tail barnamaj mowahib li mora9abat attasjilat wa nataij awamir al 7asoub. damj, talwin, mora9abat attarchi7 wa ila akhirih. http://www.vanheusden.com/multitail/ -- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.com -- Learn Graph Databases - Download FREE O'Reilly Book Graph Databases is the definitive new guide to graph databases and their applications. Written by three acclaimed leaders in the field, this first edition is now available. Download your free book today! http://p.sf.net/sfu/13534_NeoTech ___ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel -- Learn Graph Databases - Download FREE O'Reilly Book Graph Databases is the definitive new guide to graph databases and their applications. Written by three acclaimed leaders in the field, this first edition is now available. Download your free book today! http://p.sf.net/sfu/13534_NeoTech ___ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
Re: [f2fs-dev] [PATCH] f2fs: optimize fs_lock for better performance
Hi,
2013/9/11 Chao Yu chao2...@samsung.com
Hi Kim,
I did some tests as you mention of using random instead of spin_lock.
The test model is as following:
eight threads race to grab one of eight locks for one thousand times,
and I used four methods to generate lock num:
1.atomic_add_return(1, sbi-next_lock_num) % NR_GLOBAL_LOCKS;
2.spin_lock(); next_lock_num++ % NR_GLOBAL_LOCKS; spin_unlock();
3.ktime_get().tv64 % NR_GLOBAL_LOCKS;
4.get_random_bytes(next_lock, sizeof(unsigned int));
the result indicate that:
max count of collide continuously: 4 3 2 = 1
max-min count of lock is grabbed: 4 3 2 = 1
elapsed time of generating: 3 2 4 1
So I think it's better to use atomic_add_return in round-robin method to
cost less time and reduce collide.
What's your opinion?
Could you test with sbi-next_lock_num++ only instead of using
atomic_add_return?
IMO, this is just an integer value and still I don't think this value should
be covered by any kind of locks.
Thanks,
thanks
--- Original Message ---
Sender : ???jaegeuk@samsung.com S5(??)/??/?(???)/
Date : 九月 10, 2013 09:52 (GMT+09:00)
Title : Re: [f2fs-dev][PATCH] f2fs: optimize fs_lock for better performance
Hi,
At first, thank you for the report and please follow the email writing
rules. :)
Anyway, I agree to the below issue.
One thing that I can think of is that we don't need to use the
spin_lock, since we don't care about the exact lock number, but just
need to get any not-collided number.
So, how about removing the spin_lock?
And how about using a random number?
Thanks,
2013-09-06 (?), 09:48 +, Chao Yu:
Hi Kim:
I think there is a performance problem: when all sbi-fs_lock is
holded,
then all other threads may get the same next_lock value from
sbi-next_lock_num in function mutex_lock_op,
and wait to get the same lock at position fs_lock[next_lock], it
unbalance the fs_lock usage.
It may lost performance when we do the multithread test.
Here is the patch to fix this problem:
Signed-off-by: Yu Chao
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
old mode 100644
new mode 100755
index 467d42d..983bb45
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -371,6 +371,7 @@ struct f2fs_sb_info {
struct mutex fs_lock[NR_GLOBAL_LOCKS]; /* blocking FS
operations */
struct mutex node_write;/* locking node writes
*/
struct mutex writepages;/* mutex for
writepages() */
+ spinlock_t spin_lock; /* lock for
next_lock_num */
unsigned char next_lock_num;/* round-robin global
locks */
int por_doing; /* recovery is doing
or not */
int on_build_free_nids; /* build_free_nids is
doing */
@@ -533,15 +534,19 @@ static inline void mutex_unlock_all(struct
f2fs_sb_info *sbi)
static inline int mutex_lock_op(struct f2fs_sb_info *sbi)
{
- unsigned char next_lock = sbi-next_lock_num %
NR_GLOBAL_LOCKS;
+ unsigned char next_lock;
int i = 0;
for (; i NR_GLOBAL_LOCKS; i++)
if (mutex_trylock(sbi-fs_lock[i]))
return i;
- mutex_lock(sbi-fs_lock[next_lock]);
+ spin_lock(sbi-spin_lock);
+ next_lock = sbi-next_lock_num % NR_GLOBAL_LOCKS;
sbi-next_lock_num++;
+ spin_unlock(sbi-spin_lock);
+
+ mutex_lock(sbi-fs_lock[next_lock]);
return next_lock;
}
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
old mode 100644
new mode 100755
index 75c7dc3..4f27596
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -657,6 +657,7 @@ static int f2fs_fill_super(struct super_block *sb,
void *data, int silent)
mutex_init(sbi-cp_mutex);
for (i = 0; i NR_GLOBAL_LOCKS; i++)
mutex_init(sbi-fs_lock[i]);
+ spin_lock_init(sbi-spin_lock);
mutex_init(sbi-node_write);
sbi-por_doing = 0;
spin_lock_init(sbi-stat_lock);
(END)
--
Jaegeuk Kim
Samsung
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Re: [f2fs-dev] [PATCH] f2fs: optimize fs_lock for better performance
Hi Russ,
The usage of fs_locks is for the recovery, so it doesn't matter
with stress-testing.
Actually what I've concerned is that we should not grab two or
more fs_locks in the same call path.
Thanks,
2013/9/11 Russ Knize russ.kn...@motorola.com:
Hi Jaegeuk/Gu,
I've removed the lock and have been stress-testing with SELinux and some
additional xattr torture for 24+ hours. I have not encountered any issues
yet.
My previous suggestion about moving the lock is probably not a good idea
without some significant code rework (thanks to the f2fs_balance_fs call in
f2fs_setxattr).
Russ
On Tue, Sep 10, 2013 at 10:22 PM, Gu Zheng guz.f...@cn.fujitsu.com wrote:
Hi Jaegeuk,
On 09/10/2013 08:59 AM, Jaegeuk Kim wrote:
Hi,
2013-09-07 (토), 08:00 +, Chao Yu:
Hi Knize,
Thanks for your reply, I think it's actually meaningless that it's
being named after spin_lock,
it's better to rename this spinlock to round_robin_lock.
This patch can only resolve the issue of unbalanced fs_lock usage,
it can not fix the deadlock issue.
can we fix deadlock issue through this method:
- vfs_create()
- f2fs_create() - takes an fs_lock and save current thread info into
thread_info[NR_GLOBAL_LOCKS]
- f2fs_add_link()
- __f2fs_add_link()
- init_inode_metadata()
- f2fs_init_security()
- security_inode_init_security()
- f2fs_initxattrs()
- f2fs_setxattr() - get fs_lock only if there is no current
thread info in thread_info
So it keeps one thread can only hold one fs_lock to avoid deadlock.
Can we use this solution?
It could be.
But, I think we can avoid to grab the fs_lock at the f2fs_initxattrs()
Agree. This fs_lock here is used to protect the xattr from parallel
modification,
but here is in the initxattrs routine, parallel modification can not
happen.
And in the normal setxattr routine the inode-i_mutex (vfs layer) is used
to
avoid parallel modification. So I think this fs_lock is needless.
Am I missing something?
Regards,
Gu
level, since this case only happens when f2fs_initxattrs() is called.
Let's think about ut in more detail.
Thanks,
thanks again!
--- Original Message ---
Sender : Russ Knizeruss.kn...@motorola.com
Date : 九月 07, 2013 04:25 (GMT+09:00)
Title : Re: [f2fs-dev] [PATCH] f2fs: optimize fs_lock for better
performance
I encountered this same issue recently and solved it in much the same
way. Can we rename spin_lock to something more meaningful?
This race actually exposed a potential deadlock between f2fs_create()
and f2fs_initxattrs():
- vfs_create()
- f2fs_create() - takes an fs_lock
- f2fs_add_link()
- __f2fs_add_link()
- init_inode_metadata()
- f2fs_init_security()
- security_inode_init_security()
- f2fs_initxattrs()
- f2fs_setxattr() - also takes an fs_lock
If another CPU happens to have the same lock that f2fs_setxattr() was
trying to take because of the race around next_lock_num, we can get
into a deadlock situation if the two threads are also contending over
another resource (like bdi).
Another scenario is if the above happens while another thread is in
the middle of grabbing all of the locks via mutex_lock_all().
f2fs_create() is holding a lock that mutex_lock_all() is waiting for
and mutex_lock_all() is holding a lock that f2fs_setxattr() is waiting
for.
Russ
On Fri, Sep 6, 2013 at 4:48 AM, Chao Yu chao2...@samsung.com wrote:
Hi Kim:
I think there is a performance problem: when all
sbi-fs_lock is holded,
then all other threads may get the same next_lock value from
sbi-next_lock_num in function mutex_lock_op,
and wait to get the same lock at position fs_lock[next_lock],
it unbalance the fs_lock usage.
It may lost performance when we do the multithread test.
Here is the patch to fix this problem:
Signed-off-by: Yu Chao chao2...@samsung.com
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
old mode 100644
new mode 100755
index 467d42d..983bb45
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -371,6 +371,7 @@ struct f2fs_sb_info {
struct mutex fs_lock[NR_GLOBAL_LOCKS]; /* blocking FS
operations */
struct mutex node_write;/* locking
node writes */
struct mutex writepages;/* mutex for
writepages() */
+ spinlock_t spin_lock; /* lock for
next_lock_num */
unsigned char next_lock_num;/* round-robin
global locks */
int por_doing; /* recovery is
doing or not */
Re: [f2fs-dev] [PATCH] f2fs: optimize fs_lock for better performance
Hi Gu,
2013/9/11 Gu Zheng guz.f...@cn.fujitsu.com:
Hi Jaegeuk, Chao,
On 09/10/2013 08:52 AM, Jaegeuk Kim wrote:
Hi,
At first, thank you for the report and please follow the email writing
rules. :)
Anyway, I agree to the below issue.
One thing that I can think of is that we don't need to use the
spin_lock, since we don't care about the exact lock number, but just
need to get any not-collided number.
IMHO, just moving sbi-next_lock_num++ before
mutex_lock(sbi-fs_lock[next_lock])
can avoid unbalance issue mostly.
IMO, the case two or more threads increase sbi-next_lock_num in the same
time is
really very very little. If you think it is not rigorous, change
next_lock_num to
atomic one can fix it.
What's your opinion?
As your opinion, I think it is enough to replace it with simple
sbi-next_lock_num++.
Thanks,
Regards,
Gu
So, how about removing the spin_lock?
And how about using a random number?
Thanks,
2013-09-06 (금), 09:48 +, Chao Yu:
Hi Kim:
I think there is a performance problem: when all sbi-fs_lock is
holded,
then all other threads may get the same next_lock value from
sbi-next_lock_num in function mutex_lock_op,
and wait to get the same lock at position fs_lock[next_lock], it
unbalance the fs_lock usage.
It may lost performance when we do the multithread test.
Here is the patch to fix this problem:
Signed-off-by: Yu Chao chao2...@samsung.com
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
old mode 100644
new mode 100755
index 467d42d..983bb45
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -371,6 +371,7 @@ struct f2fs_sb_info {
struct mutex fs_lock[NR_GLOBAL_LOCKS]; /* blocking FS
operations */
struct mutex node_write;/* locking node writes
*/
struct mutex writepages;/* mutex for
writepages() */
+ spinlock_t spin_lock; /* lock for
next_lock_num */
unsigned char next_lock_num;/* round-robin global
locks */
int por_doing; /* recovery is doing
or not */
int on_build_free_nids; /* build_free_nids is
doing */
@@ -533,15 +534,19 @@ static inline void mutex_unlock_all(struct
f2fs_sb_info *sbi)
static inline int mutex_lock_op(struct f2fs_sb_info *sbi)
{
- unsigned char next_lock = sbi-next_lock_num %
NR_GLOBAL_LOCKS;
+ unsigned char next_lock;
int i = 0;
for (; i NR_GLOBAL_LOCKS; i++)
if (mutex_trylock(sbi-fs_lock[i]))
return i;
- mutex_lock(sbi-fs_lock[next_lock]);
+ spin_lock(sbi-spin_lock);
+ next_lock = sbi-next_lock_num % NR_GLOBAL_LOCKS;
sbi-next_lock_num++;
+ spin_unlock(sbi-spin_lock);
+
+ mutex_lock(sbi-fs_lock[next_lock]);
return next_lock;
}
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
old mode 100644
new mode 100755
index 75c7dc3..4f27596
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -657,6 +657,7 @@ static int f2fs_fill_super(struct super_block *sb,
void *data, int silent)
mutex_init(sbi-cp_mutex);
for (i = 0; i NR_GLOBAL_LOCKS; i++)
mutex_init(sbi-fs_lock[i]);
+ spin_lock_init(sbi-spin_lock);
mutex_init(sbi-node_write);
sbi-por_doing = 0;
spin_lock_init(sbi-stat_lock);
(END)
--
How ServiceNow helps IT people transform IT departments:
1. Consolidate legacy IT systems to a single system of record for IT
2. Standardize and globalize service processes across IT
3. Implement zero-touch automation to replace manual, redundant tasks
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2. Standardize and globalize service processes across IT
3. Implement zero-touch automation to replace manual, redundant tasks
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