forked from Minki/linux
reiserfs: Fix reiserfs lock <-> i_xattr_sem dependency inversion
i_xattr_sem depends on the reiserfs lock. But after we grab i_xattr_sem, we may relax/relock the reiserfs lock while waiting on a freezed filesystem, creating a dependency inversion between the two locks. In order to avoid the i_xattr_sem -> reiserfs lock dependency, let's create a reiserfs_down_read_safe() that acts like reiserfs_mutex_lock_safe(): relax the reiserfs lock while grabbing another lock to avoid undesired dependencies induced by the heivyweight reiserfs lock. This fixes the following warning: [ 990.005931] ======================================================= [ 990.012373] [ INFO: possible circular locking dependency detected ] [ 990.013233] 2.6.33-rc1 #1 [ 990.013233] ------------------------------------------------------- [ 990.013233] dbench/1891 is trying to acquire lock: [ 990.013233] (&REISERFS_SB(s)->lock){+.+.+.}, at: [<ffffffff81159505>] reiserfs_write_lock+0x35/0x50 [ 990.013233] [ 990.013233] but task is already holding lock: [ 990.013233] (&REISERFS_I(inode)->i_xattr_sem){+.+.+.}, at: [<ffffffff8115899a>] reiserfs_xattr_set_handle+0x8a/0x470 [ 990.013233] [ 990.013233] which lock already depends on the new lock. [ 990.013233] [ 990.013233] [ 990.013233] the existing dependency chain (in reverse order) is: [ 990.013233] [ 990.013233] -> #1 (&REISERFS_I(inode)->i_xattr_sem){+.+.+.}: [ 990.013233] [<ffffffff81063afc>] __lock_acquire+0xf9c/0x1560 [ 990.013233] [<ffffffff8106414f>] lock_acquire+0x8f/0xb0 [ 990.013233] [<ffffffff814ac194>] down_write+0x44/0x80 [ 990.013233] [<ffffffff8115899a>] reiserfs_xattr_set_handle+0x8a/0x470 [ 990.013233] [<ffffffff81158e30>] reiserfs_xattr_set+0xb0/0x150 [ 990.013233] [<ffffffff8115a6aa>] user_set+0x8a/0x90 [ 990.013233] [<ffffffff8115901a>] reiserfs_setxattr+0xaa/0xb0 [ 990.013233] [<ffffffff810e2596>] __vfs_setxattr_noperm+0x36/0xa0 [ 990.013233] [<ffffffff810e26bc>] vfs_setxattr+0xbc/0xc0 [ 990.013233] [<ffffffff810e2780>] setxattr+0xc0/0x150 [ 990.013233] [<ffffffff810e289d>] sys_fsetxattr+0x8d/0xa0 [ 990.013233] [<ffffffff81002dab>] system_call_fastpath+0x16/0x1b [ 990.013233] [ 990.013233] -> #0 (&REISERFS_SB(s)->lock){+.+.+.}: [ 990.013233] [<ffffffff81063e30>] __lock_acquire+0x12d0/0x1560 [ 990.013233] [<ffffffff8106414f>] lock_acquire+0x8f/0xb0 [ 990.013233] [<ffffffff814aba77>] __mutex_lock_common+0x47/0x3b0 [ 990.013233] [<ffffffff814abebe>] mutex_lock_nested+0x3e/0x50 [ 990.013233] [<ffffffff81159505>] reiserfs_write_lock+0x35/0x50 [ 990.013233] [<ffffffff811340e5>] reiserfs_prepare_write+0x45/0x180 [ 990.013233] [<ffffffff81158bb6>] reiserfs_xattr_set_handle+0x2a6/0x470 [ 990.013233] [<ffffffff81158e30>] reiserfs_xattr_set+0xb0/0x150 [ 990.013233] [<ffffffff8115a6aa>] user_set+0x8a/0x90 [ 990.013233] [<ffffffff8115901a>] reiserfs_setxattr+0xaa/0xb0 [ 990.013233] [<ffffffff810e2596>] __vfs_setxattr_noperm+0x36/0xa0 [ 990.013233] [<ffffffff810e26bc>] vfs_setxattr+0xbc/0xc0 [ 990.013233] [<ffffffff810e2780>] setxattr+0xc0/0x150 [ 990.013233] [<ffffffff810e289d>] sys_fsetxattr+0x8d/0xa0 [ 990.013233] [<ffffffff81002dab>] system_call_fastpath+0x16/0x1b [ 990.013233] [ 990.013233] other info that might help us debug this: [ 990.013233] [ 990.013233] 2 locks held by dbench/1891: [ 990.013233] #0: (&sb->s_type->i_mutex_key#12){+.+.+.}, at: [<ffffffff810e2678>] vfs_setxattr+0x78/0xc0 [ 990.013233] #1: (&REISERFS_I(inode)->i_xattr_sem){+.+.+.}, at: [<ffffffff8115899a>] reiserfs_xattr_set_handle+0x8a/0x470 [ 990.013233] [ 990.013233] stack backtrace: [ 990.013233] Pid: 1891, comm: dbench Not tainted 2.6.33-rc1 #1 [ 990.013233] Call Trace: [ 990.013233] [<ffffffff81061639>] print_circular_bug+0xe9/0xf0 [ 990.013233] [<ffffffff81063e30>] __lock_acquire+0x12d0/0x1560 [ 990.013233] [<ffffffff8115899a>] ? reiserfs_xattr_set_handle+0x8a/0x470 [ 990.013233] [<ffffffff8106414f>] lock_acquire+0x8f/0xb0 [ 990.013233] [<ffffffff81159505>] ? reiserfs_write_lock+0x35/0x50 [ 990.013233] [<ffffffff8115899a>] ? reiserfs_xattr_set_handle+0x8a/0x470 [ 990.013233] [<ffffffff814aba77>] __mutex_lock_common+0x47/0x3b0 [ 990.013233] [<ffffffff81159505>] ? reiserfs_write_lock+0x35/0x50 [ 990.013233] [<ffffffff81159505>] ? reiserfs_write_lock+0x35/0x50 [ 990.013233] [<ffffffff81062592>] ? mark_held_locks+0x72/0xa0 [ 990.013233] [<ffffffff814ab81d>] ? __mutex_unlock_slowpath+0xbd/0x140 [ 990.013233] [<ffffffff810628ad>] ? trace_hardirqs_on_caller+0x14d/0x1a0 [ 990.013233] [<ffffffff814abebe>] mutex_lock_nested+0x3e/0x50 [ 990.013233] [<ffffffff81159505>] reiserfs_write_lock+0x35/0x50 [ 990.013233] [<ffffffff811340e5>] reiserfs_prepare_write+0x45/0x180 [ 990.013233] [<ffffffff81158bb6>] reiserfs_xattr_set_handle+0x2a6/0x470 [ 990.013233] [<ffffffff81158e30>] reiserfs_xattr_set+0xb0/0x150 [ 990.013233] [<ffffffff814abcb4>] ? __mutex_lock_common+0x284/0x3b0 [ 990.013233] [<ffffffff8115a6aa>] user_set+0x8a/0x90 [ 990.013233] [<ffffffff8115901a>] reiserfs_setxattr+0xaa/0xb0 [ 990.013233] [<ffffffff810e2596>] __vfs_setxattr_noperm+0x36/0xa0 [ 990.013233] [<ffffffff810e26bc>] vfs_setxattr+0xbc/0xc0 [ 990.013233] [<ffffffff810e2780>] setxattr+0xc0/0x150 [ 990.013233] [<ffffffff81056018>] ? sched_clock_cpu+0xb8/0x100 [ 990.013233] [<ffffffff8105eded>] ? trace_hardirqs_off+0xd/0x10 [ 990.013233] [<ffffffff810560a3>] ? cpu_clock+0x43/0x50 [ 990.013233] [<ffffffff810c6820>] ? fget+0xb0/0x110 [ 990.013233] [<ffffffff810c6770>] ? fget+0x0/0x110 [ 990.013233] [<ffffffff81002ddc>] ? sysret_check+0x27/0x62 [ 990.013233] [<ffffffff810e289d>] sys_fsetxattr+0x8d/0xa0 [ 990.013233] [<ffffffff81002dab>] system_call_fastpath+0x16/0x1b Reported-and-tested-by: Christian Kujau <lists@nerdbynature.de> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Alexander Beregalov <a.beregalov@gmail.com> Cc: Chris Mason <chris.mason@oracle.com> Cc: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Frederic Weisbecker
parent
98ea3f50bc
commit
0719d34347
@ -484,7 +484,7 @@ reiserfs_xattr_set_handle(struct reiserfs_transaction_handle *th,
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if (IS_ERR(dentry))
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if (IS_ERR(dentry))
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return PTR_ERR(dentry);
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return PTR_ERR(dentry);
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down_write(&REISERFS_I(inode)->i_xattr_sem);
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reiserfs_down_read_safe(&REISERFS_I(inode)->i_xattr_sem, inode->i_sb);
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xahash = xattr_hash(buffer, buffer_size);
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xahash = xattr_hash(buffer, buffer_size);
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while (buffer_pos < buffer_size || buffer_pos == 0) {
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while (buffer_pos < buffer_size || buffer_pos == 0) {
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@ -106,6 +106,14 @@ reiserfs_mutex_lock_nested_safe(struct mutex *m, unsigned int subclass,
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reiserfs_write_lock(s);
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reiserfs_write_lock(s);
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}
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}
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static inline void
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reiserfs_down_read_safe(struct rw_semaphore *sem, struct super_block *s)
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{
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reiserfs_write_unlock(s);
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down_read(sem);
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reiserfs_write_lock(s);
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}
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/*
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/*
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* When we schedule, we usually want to also release the write lock,
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* When we schedule, we usually want to also release the write lock,
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* according to the previous bkl based locking scheme of reiserfs.
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* according to the previous bkl based locking scheme of reiserfs.
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