From 1154ecbd2f8298ef75609f5f8ed5aca96be599fb Mon Sep 17 00:00:00 2001 From: Zhang Qiang Date: Tue, 18 Aug 2009 14:58:24 +0800 Subject: nilfs2: missing a read lock for segment writer in nilfs_attach_checkpoint() 'ns_cno' of structure 'the_nilfs' must be protected from segment writer, in other words, the caller of nilfs_get_checkpoint should hold read lock for nilfs->ns_segctor_sem. This patch adds the lock/unlock operations in nilfs_attach_checkpoint() when calling nilfs_cpfile_get_checkpoint(). Signed-off-by: Zhang Qiang Signed-off-by: Ryusuke Konishi --- fs/nilfs2/super.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'fs') diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c index 8e2ec43b18f4..151964f0de4c 100644 --- a/fs/nilfs2/super.c +++ b/fs/nilfs2/super.c @@ -416,8 +416,10 @@ int nilfs_attach_checkpoint(struct nilfs_sb_info *sbi, __u64 cno) if (unlikely(err)) goto failed; + down_read(&nilfs->ns_segctor_sem); err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, cno, 0, &raw_cp, &bh_cp); + up_read(&nilfs->ns_segctor_sem); if (unlikely(err)) { if (err == -ENOENT || err == -EINVAL) { printk(KERN_ERR -- cgit v1.2.1 From a924586036833086b262a371b09d1266c23bb4d1 Mon Sep 17 00:00:00 2001 From: Ryusuke Konishi Date: Wed, 19 Aug 2009 00:29:43 +0900 Subject: nilfs2: fix oopses with doubly mounted snapshots will fix kernel oopses like the following: # mount -t nilfs2 -r -o cp=20 /dev/sdb1 /test1 # mount -t nilfs2 -r -o cp=20 /dev/sdb1 /test2 # umount /test1 # umount /test2 BUG: sleeping function called from invalid context at arch/x86/mm/fault.c:1069 in_atomic(): 0, irqs_disabled(): 1, pid: 3886, name: umount.nilfs2 1 lock held by umount.nilfs2/3886: #0: (&type->s_umount_key#31){+.+...}, at: [] deactivate_super+0x52/0x6c irq event stamp: 1219 hardirqs last enabled at (1219): [] __mutex_unlock_slowpath+0xf8/0x119 hardirqs last disabled at (1218): [] __mutex_unlock_slowpath+0x59/0x119 softirqs last enabled at (1214): [] __do_softirq+0x1a5/0x1ad softirqs last disabled at (1205): [] do_softirq+0x36/0x5a Pid: 3886, comm: umount.nilfs2 Not tainted 2.6.31-rc6 #55 Call Trace: [] __might_sleep+0x107/0x10e [] do_page_fault+0x246/0x397 [] ? do_page_fault+0x0/0x397 [] error_code+0x6b/0x70 [] ? do_page_fault+0x0/0x397 [] ? __lock_acquire+0x91/0x12fd [] ? __lock_acquire+0x12ee/0x12fd [] ? __lock_acquire+0x12ee/0x12fd [] lock_acquire+0xba/0xdd [] ? nilfs_detach_segment_constructor+0x2f/0x2fa [nilfs2] [] down_write+0x2a/0x46 [] ? nilfs_detach_segment_constructor+0x2f/0x2fa [nilfs2] [] nilfs_detach_segment_constructor+0x2f/0x2fa [nilfs2] [] ? mark_held_locks+0x43/0x5b [] ? trace_hardirqs_on_caller+0x10b/0x133 [] ? trace_hardirqs_on+0xb/0xd [] nilfs_put_super+0x2f/0xca [nilfs2] [] generic_shutdown_super+0x49/0xb8 [] kill_block_super+0x1d/0x31 [] ? vfs_quota_off+0x0/0x12 [] deactivate_super+0x57/0x6c [] mntput_no_expire+0x8c/0xb4 [] sys_umount+0x27f/0x2a4 [] sys_oldumount+0xd/0xf [] sysenter_do_call+0x12/0x38 ... This turns out to be a bug brought by an -rc1 patch ("nilfs2: simplify remaining sget() use"). In the patch, a new "put resource" function, nilfs_put_sbinfo() was introduced to delay freeing nilfs_sb_info struct. But the nilfs_put_sbinfo() mistakenly used atomic_dec_and_test() function to check the reference count, and it caused the nilfs_sb_info was freed when user mounted a snapshot twice. This bug also suggests there was unseen memory leak in usual mount /umount operations for nilfs. Signed-off-by: Ryusuke Konishi --- fs/nilfs2/the_nilfs.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs') diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h index e8adbffc626f..1b9caafb8662 100644 --- a/fs/nilfs2/the_nilfs.h +++ b/fs/nilfs2/the_nilfs.h @@ -253,7 +253,7 @@ nilfs_detach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi) static inline void nilfs_put_sbinfo(struct nilfs_sb_info *sbi) { - if (!atomic_dec_and_test(&sbi->s_count)) + if (atomic_dec_and_test(&sbi->s_count)) kfree(sbi); } -- cgit v1.2.1