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author | 2018-10-12 15:32:32 -0400 | |
---|---|---|
committer | 2018-10-19 12:20:04 +0200 | |
commit | c495144bc6962186feae31d687596d2472000e45 (patch) | |
tree | c17e15559aed1a066fce1ee363017dc27977fd19 /fs/btrfs | |
parent | btrfs: don't run delayed_iputs in commit (diff) | |
download | linux-c495144bc6962186feae31d687596d2472000e45.tar.gz linux-c495144bc6962186feae31d687596d2472000e45.tar.bz2 linux-c495144bc6962186feae31d687596d2472000e45.zip |
btrfs: move the dio_sem higher up the callchain
We're getting a lockdep splat because we take the dio_sem under the
log_mutex. What we really need is to protect fsync() from logging an
extent map for an extent we never waited on higher up, so just guard the
whole thing with dio_sem.
======================================================
WARNING: possible circular locking dependency detected
4.18.0-rc4-xfstests-00025-g5de5edbaf1d4 #411 Not tainted
------------------------------------------------------
aio-dio-invalid/30928 is trying to acquire lock:
0000000092621cfd (&mm->mmap_sem){++++}, at: get_user_pages_unlocked+0x5a/0x1e0
but task is already holding lock:
00000000cefe6b35 (&ei->dio_sem){++++}, at: btrfs_direct_IO+0x3be/0x400
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #5 (&ei->dio_sem){++++}:
lock_acquire+0xbd/0x220
down_write+0x51/0xb0
btrfs_log_changed_extents+0x80/0xa40
btrfs_log_inode+0xbaf/0x1000
btrfs_log_inode_parent+0x26f/0xa80
btrfs_log_dentry_safe+0x50/0x70
btrfs_sync_file+0x357/0x540
do_fsync+0x38/0x60
__ia32_sys_fdatasync+0x12/0x20
do_fast_syscall_32+0x9a/0x2f0
entry_SYSENTER_compat+0x84/0x96
-> #4 (&ei->log_mutex){+.+.}:
lock_acquire+0xbd/0x220
__mutex_lock+0x86/0xa10
btrfs_record_unlink_dir+0x2a/0xa0
btrfs_unlink+0x5a/0xc0
vfs_unlink+0xb1/0x1a0
do_unlinkat+0x264/0x2b0
do_fast_syscall_32+0x9a/0x2f0
entry_SYSENTER_compat+0x84/0x96
-> #3 (sb_internal#2){.+.+}:
lock_acquire+0xbd/0x220
__sb_start_write+0x14d/0x230
start_transaction+0x3e6/0x590
btrfs_evict_inode+0x475/0x640
evict+0xbf/0x1b0
btrfs_run_delayed_iputs+0x6c/0x90
cleaner_kthread+0x124/0x1a0
kthread+0x106/0x140
ret_from_fork+0x3a/0x50
-> #2 (&fs_info->cleaner_delayed_iput_mutex){+.+.}:
lock_acquire+0xbd/0x220
__mutex_lock+0x86/0xa10
btrfs_alloc_data_chunk_ondemand+0x197/0x530
btrfs_check_data_free_space+0x4c/0x90
btrfs_delalloc_reserve_space+0x20/0x60
btrfs_page_mkwrite+0x87/0x520
do_page_mkwrite+0x31/0xa0
__handle_mm_fault+0x799/0xb00
handle_mm_fault+0x7c/0xe0
__do_page_fault+0x1d3/0x4a0
async_page_fault+0x1e/0x30
-> #1 (sb_pagefaults){.+.+}:
lock_acquire+0xbd/0x220
__sb_start_write+0x14d/0x230
btrfs_page_mkwrite+0x6a/0x520
do_page_mkwrite+0x31/0xa0
__handle_mm_fault+0x799/0xb00
handle_mm_fault+0x7c/0xe0
__do_page_fault+0x1d3/0x4a0
async_page_fault+0x1e/0x30
-> #0 (&mm->mmap_sem){++++}:
__lock_acquire+0x42e/0x7a0
lock_acquire+0xbd/0x220
down_read+0x48/0xb0
get_user_pages_unlocked+0x5a/0x1e0
get_user_pages_fast+0xa4/0x150
iov_iter_get_pages+0xc3/0x340
do_direct_IO+0xf93/0x1d70
__blockdev_direct_IO+0x32d/0x1c20
btrfs_direct_IO+0x227/0x400
generic_file_direct_write+0xcf/0x180
btrfs_file_write_iter+0x308/0x58c
aio_write+0xf8/0x1d0
io_submit_one+0x3a9/0x620
__ia32_compat_sys_io_submit+0xb2/0x270
do_int80_syscall_32+0x5b/0x1a0
entry_INT80_compat+0x88/0xa0
other info that might help us debug this:
Chain exists of:
&mm->mmap_sem --> &ei->log_mutex --> &ei->dio_sem
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&ei->dio_sem);
lock(&ei->log_mutex);
lock(&ei->dio_sem);
lock(&mm->mmap_sem);
*** DEADLOCK ***
1 lock held by aio-dio-invalid/30928:
#0: 00000000cefe6b35 (&ei->dio_sem){++++}, at: btrfs_direct_IO+0x3be/0x400
stack backtrace:
CPU: 0 PID: 30928 Comm: aio-dio-invalid Not tainted 4.18.0-rc4-xfstests-00025-g5de5edbaf1d4 #411
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 04/01/2014
Call Trace:
dump_stack+0x7c/0xbb
print_circular_bug.isra.37+0x297/0x2a4
check_prev_add.constprop.45+0x781/0x7a0
? __lock_acquire+0x42e/0x7a0
validate_chain.isra.41+0x7f0/0xb00
__lock_acquire+0x42e/0x7a0
lock_acquire+0xbd/0x220
? get_user_pages_unlocked+0x5a/0x1e0
down_read+0x48/0xb0
? get_user_pages_unlocked+0x5a/0x1e0
get_user_pages_unlocked+0x5a/0x1e0
get_user_pages_fast+0xa4/0x150
iov_iter_get_pages+0xc3/0x340
do_direct_IO+0xf93/0x1d70
? __alloc_workqueue_key+0x358/0x490
? __blockdev_direct_IO+0x14b/0x1c20
__blockdev_direct_IO+0x32d/0x1c20
? btrfs_run_delalloc_work+0x40/0x40
? can_nocow_extent+0x490/0x490
? kvm_clock_read+0x1f/0x30
? can_nocow_extent+0x490/0x490
? btrfs_run_delalloc_work+0x40/0x40
btrfs_direct_IO+0x227/0x400
? btrfs_run_delalloc_work+0x40/0x40
generic_file_direct_write+0xcf/0x180
btrfs_file_write_iter+0x308/0x58c
aio_write+0xf8/0x1d0
? kvm_clock_read+0x1f/0x30
? __might_fault+0x3e/0x90
io_submit_one+0x3a9/0x620
? io_submit_one+0xe5/0x620
__ia32_compat_sys_io_submit+0xb2/0x270
do_int80_syscall_32+0x5b/0x1a0
entry_INT80_compat+0x88/0xa0
CC: stable@vger.kernel.org # 4.14+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs')
-rw-r--r-- | fs/btrfs/file.c | 12 | ||||
-rw-r--r-- | fs/btrfs/tree-log.c | 2 |
2 files changed, 12 insertions, 2 deletions
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 15b925142793..97c7a086f7bd 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -2078,6 +2078,14 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync) goto out; inode_lock(inode); + + /* + * We take the dio_sem here because the tree log stuff can race with + * lockless dio writes and get an extent map logged for an extent we + * never waited on. We need it this high up for lockdep reasons. + */ + down_write(&BTRFS_I(inode)->dio_sem); + atomic_inc(&root->log_batch); /* @@ -2086,6 +2094,7 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync) */ ret = btrfs_wait_ordered_range(inode, start, len); if (ret) { + up_write(&BTRFS_I(inode)->dio_sem); inode_unlock(inode); goto out; } @@ -2109,6 +2118,7 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync) * checked called fsync. */ ret = filemap_check_wb_err(inode->i_mapping, file->f_wb_err); + up_write(&BTRFS_I(inode)->dio_sem); inode_unlock(inode); goto out; } @@ -2127,6 +2137,7 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync) trans = btrfs_start_transaction(root, 0); if (IS_ERR(trans)) { ret = PTR_ERR(trans); + up_write(&BTRFS_I(inode)->dio_sem); inode_unlock(inode); goto out; } @@ -2148,6 +2159,7 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync) * file again, but that will end up using the synchronization * inside btrfs_sync_log to keep things safe. */ + up_write(&BTRFS_I(inode)->dio_sem); inode_unlock(inode); /* diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index 7147d329ddbc..e07f3376b7df 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -4390,7 +4390,6 @@ static int btrfs_log_changed_extents(struct btrfs_trans_handle *trans, INIT_LIST_HEAD(&extents); - down_write(&inode->dio_sem); write_lock(&tree->lock); test_gen = root->fs_info->last_trans_committed; logged_start = start; @@ -4456,7 +4455,6 @@ process: } WARN_ON(!list_empty(&extents)); write_unlock(&tree->lock); - up_write(&inode->dio_sem); btrfs_release_path(path); if (!ret) |