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ce7791ffee
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Filipe Manana ce7791ffee Btrfs: fix race between readahead and device replace/removal 
The list of devices is protected by the device_list_mutex and the device
replace code, in its finishing phase correctly takes that mutex before
removing the source device from that list. However the readahead code was
iterating that list without acquiring the respective mutex leading to
crashes later on due to invalid memory accesses:

[125671.831036] general protection fault: 0000 [#1] PREEMPT SMP
[125671.832129] Modules linked in: btrfs dm_flakey dm_mod crc32c_generic xor raid6_pq acpi_cpufreq tpm_tis tpm ppdev evdev parport_pc psmouse sg parport
processor ser
[125671.834973] CPU: 10 PID: 19603 Comm: kworker/u32:19 Tainted: G        W       4.6.0-rc7-btrfs-next-29+ #1
[125671.834973] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS by qemu-project.org 04/01/2014
[125671.834973] Workqueue: btrfs-readahead btrfs_readahead_helper [btrfs]
[125671.834973] task: ffff8801ac520540 ti: ffff8801ac918000 task.ti: ffff8801ac918000
[125671.834973] RIP: 0010:[<ffffffff81270479>]  [<ffffffff81270479>] __radix_tree_lookup+0x6a/0x105
[125671.834973] RSP: 0018:ffff8801ac91bc28  EFLAGS: 00010206
[125671.834973] RAX: 0000000000000000 RBX: 6b6b6b6b6b6b6b6a RCX: 0000000000000000
[125671.834973] RDX: 0000000000000000 RSI: 00000000000c1bff RDI: ffff88002ebd62a8
[125671.834973] RBP: ffff8801ac91bc70 R08: 0000000000000001 R09: 0000000000000000
[125671.834973] R10: ffff8801ac91bc70 R11: 0000000000000000 R12: ffff88002ebd62a8
[125671.834973] R13: 0000000000000000 R14: 0000000000000000 R15: 00000000000c1bff
[125671.834973] FS:  0000000000000000(0000) GS:ffff88023fd40000(0000) knlGS:0000000000000000
[125671.834973] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[125671.834973] CR2: 000000000073cae4 CR3: 00000000b7723000 CR4: 00000000000006e0
[125671.834973] Stack:
[125671.834973]  0000000000000000 ffff8801422d5600 ffff8802286bbc00 0000000000000000
[125671.834973]  0000000000000001 ffff8802286bbc00 00000000000c1bff 0000000000000000
[125671.834973]  ffff88002e639eb8 ffff8801ac91bc80 ffffffff81270541 ffff8801ac91bcb0
[125671.834973] Call Trace:
[125671.834973]  [<ffffffff81270541>] radix_tree_lookup+0xd/0xf
[125671.834973]  [<ffffffffa04ae6a6>] reada_peer_zones_set_lock+0x3e/0x60 [btrfs]
[125671.834973]  [<ffffffffa04ae8b9>] reada_pick_zone+0x29/0x103 [btrfs]
[125671.834973]  [<ffffffffa04af42f>] reada_start_machine_worker+0x129/0x2d3 [btrfs]
[125671.834973]  [<ffffffffa04880be>] btrfs_scrubparity_helper+0x185/0x3aa [btrfs]
[125671.834973]  [<ffffffffa0488341>] btrfs_readahead_helper+0xe/0x10 [btrfs]
[125671.834973]  [<ffffffff81069691>] process_one_work+0x271/0x4e9
[125671.834973]  [<ffffffff81069dda>] worker_thread+0x1eb/0x2c9
[125671.834973]  [<ffffffff81069bef>] ? rescuer_thread+0x2b3/0x2b3
[125671.834973]  [<ffffffff8106f403>] kthread+0xd4/0xdc
[125671.834973]  [<ffffffff8149e242>] ret_from_fork+0x22/0x40
[125671.834973]  [<ffffffff8106f32f>] ? kthread_stop+0x286/0x286

So fix this by taking the device_list_mutex in the readahead code. We
can't use here the lighter approach of using a rcu_read_lock() and
rcu_read_unlock() pair together with a list_for_each_entry_rcu() call
because we end up doing calls to sleeping functions (kzalloc()) in the
respective code path.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
2016-05-30 12:58:18 +01:00
..
tests btrfs: fix string and comment grammatical issues and typos 2016-05-25 22:35:14 +02:00
acl.c Merge branch 'for-linus-4.5' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs 2016-01-18 12:44:40 -08:00
async-thread.c btrfs: async-thread: Fix a use-after-free error for trace 2016-01-25 16:50:26 -08:00
async-thread.h btrfs: async_thread: Fix workqueue 'max_active' value when initializing 2015-08-31 11:46:40 -07:00
backref.c Merge branch 'cleanups-4.7' into for-chris-4.7-20160525 2016-05-25 22:51:03 +02:00
backref.h btrfs: cleanup, remove inode_item_info helper 2015-01-14 19:23:47 +01:00
btrfs_inode.h Merge branch 'cleanups-4.7' into for-chris-4.7-20160525 2016-05-25 22:51:03 +02:00
check-integrity.c btrfs: fix string and comment grammatical issues and typos 2016-05-25 22:35:14 +02:00
check-integrity.h
compression.c btrfs: make find_workspace warn if there are no workspaces 2016-05-10 09:46:16 +02:00
compression.h btrfs: move btrfs_compression_type to compression.h 2016-03-11 17:12:46 +01:00
ctree.c Merge branch 'cleanups-4.7' into for-chris-4.7-20160525 2016-05-25 22:51:03 +02:00
ctree.h Merge branch 'cleanups-4.7' into for-chris-4.7-20160525 2016-05-25 22:51:03 +02:00
delayed-inode.c btrfs: GFP_NOFS does not GFP_HIGHMEM 2016-05-10 09:44:21 +02:00
delayed-inode.h btrfs: properly set the termination value of ctx->pos in readdir 2016-02-11 07:01:59 -08:00
delayed-ref.c btrfs: drop null testing before destroy functions 2016-02-18 11:46:03 +01:00
delayed-ref.h btrfs: fix string and comment grammatical issues and typos 2016-05-25 22:35:14 +02:00
dev-replace.c Merge branch 'cleanups-4.7' into for-chris-4.7-20160525 2016-05-25 22:51:03 +02:00
dev-replace.h btrfs: refactor btrfs_dev_replace_start for reuse 2016-04-28 10:59:13 +02:00
dir-item.c Btrfs: make xattr replace operations atomic 2014-11-20 17:20:07 -08:00
disk-io.c Merge branch 'cleanups-4.7' into for-chris-4.7-20160525 2016-05-25 22:51:03 +02:00
disk-io.h Merge branch 'misc-cleanups-4.5' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux into for-linus-4.5 2016-01-11 06:08:37 -08:00
export.c BTRFS: support NFSv2 export 2015-10-06 06:55:23 -07:00
export.h
extent_io.c Merge branch 'cleanups-4.7' into for-chris-4.7-20160525 2016-05-25 22:51:03 +02:00
extent_io.h Merge branch 'cleanups-4.7' into for-chris-4.7-20160525 2016-05-25 22:51:03 +02:00
extent_map.c btrfs: fix string and comment grammatical issues and typos 2016-05-25 22:35:14 +02:00
extent_map.h btrfs: cleanup, stop casting for extent_map->lookup everywhere 2016-01-15 19:22:28 +01:00
extent-tree.c Merge branch 'cleanups-4.7' into for-chris-4.7-20160525 2016-05-25 22:51:03 +02:00
file-item.c btrfs: sink gfp parameter to set_extent_bits 2016-04-29 11:01:47 +02:00
file.c Btrfs: fix handling of faults from btrfs_copy_from_user 2016-05-26 13:23:59 -07:00
free-space-cache.c btrfs: fix string and comment grammatical issues and typos 2016-05-25 22:35:14 +02:00
free-space-cache.h btrfs: fix string and comment grammatical issues and typos 2016-05-25 22:35:14 +02:00
free-space-tree.c Revert "btrfs: synchronize incompat feature bits with sysfs files" 2016-01-29 08:19:37 -08:00
free-space-tree.h Btrfs: implement the free space B-tree 2015-12-17 12:16:47 -08:00
hash.c btrfs: LLVMLinux: Remove VLAIS 2014-10-14 10:51:22 +02:00
hash.h
inode-item.c btrfs: rename btrfs_std_error to btrfs_handle_fs_error 2016-04-28 10:36:54 +02:00
inode-map.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
inode-map.h Btrfs: Initialize btrfs_root->highest_objectid when loading tree root and subvolume roots 2016-01-15 19:25:02 +01:00
inode.c Merge branch 'cleanups-4.7' into for-chris-4.7-20160525 2016-05-25 22:51:03 +02:00
ioctl.c Merge branch 'cleanups-4.7' into for-chris-4.7-20160525 2016-05-25 22:51:03 +02:00
Kconfig rcu: Make SRCU optional by using CONFIG_SRCU 2015-01-06 11:04:29 -08:00
locking.c btrfs: cleanup, remove stray return statements 2016-01-07 14:30:52 +01:00
locking.h btrfs: fix lockups from btrfs_clear_path_blocking 2014-11-19 10:34:35 -08:00
lzo.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
Makefile Btrfs: add free space tree sanity tests 2015-12-17 12:16:47 -08:00
math.h btrfs: cleanup 64bit/32bit divs, compile time constants 2015-03-03 17:23:57 +01:00
ordered-data.c Btrfs: don't wait for unrelated IO to finish before relocation 2016-05-13 01:59:14 +01:00
ordered-data.h Merge branch 'cleanups-4.7' into for-chris-4.7-20160525 2016-05-25 22:51:03 +02:00
orphan.c btrfs: kill the key type accessor helpers 2014-09-17 13:37:12 -07:00
print-tree.c btrfs: teach print_leaf about temporary item subtypes 2016-02-11 16:15:43 +01:00
print-tree.h
props.c btrfs: move btrfs_compression_type to compression.h 2016-03-11 17:12:46 +01:00
props.h
qgroup.c btrfs: fix string and comment grammatical issues and typos 2016-05-25 22:35:14 +02:00
qgroup.h btrfs: qgroup: Check if qgroup reserved space leaked 2015-10-21 18:41:10 -07:00
raid56.c btrfs: fix string and comment grammatical issues and typos 2016-05-25 22:35:14 +02:00
raid56.h Btrfs: add RAID 5/6 BTRFS_RBIO_REBUILD_MISSING operation 2015-08-09 07:34:26 -07:00
rcu-string.h
reada.c Btrfs: fix race between readahead and device replace/removal 2016-05-30 12:58:18 +01:00
relocation.c Merge branch 'cleanups-4.7' into for-chris-4.7-20160525 2016-05-25 22:51:03 +02:00
root-tree.c Merge branch 'cleanups-4.7' into for-chris-4.7-20160525 2016-05-25 22:51:03 +02:00
scrub.c Merge branch 'cleanups-4.7' into for-chris-4.7-20160525 2016-05-25 22:51:03 +02:00
send.c Merge branch 'cleanups-4.7' into for-chris-4.7-20160525 2016-05-25 22:51:03 +02:00
send.h Btrfs: use linux/sizes.h to represent constants 2016-01-07 14:38:02 +01:00
struct-funcs.c btrfs: fix string and comment grammatical issues and typos 2016-05-25 22:35:14 +02:00
super.c Merge branch 'cleanups-4.7' into for-chris-4.7-20160525 2016-05-25 22:51:03 +02:00
sysfs.c btrfs: sysfs: protect reading label by lock 2016-05-06 15:22:49 +02:00
sysfs.h btrfs: sysfs: introduce helper for syncing bits with sysfs files 2016-01-21 18:50:40 +01:00
transaction.c Merge branch 'cleanups-4.7' into for-chris-4.7-20160525 2016-05-25 22:51:03 +02:00
transaction.h btrfs: fix string and comment grammatical issues and typos 2016-05-25 22:35:14 +02:00
tree-defrag.c Btrfs: fix locking bugs when defragging leaves 2015-12-18 02:51:32 +00:00
tree-log.c Merge branch 'cleanups-4.7' into for-chris-4.7-20160525 2016-05-25 22:51:03 +02:00
tree-log.h Btrfs: fix unreplayable log after snapshot delete + parent dir fsync 2016-03-01 08:23:25 -08:00
ulist.c btrfs: fix string and comment grammatical issues and typos 2016-05-25 22:35:14 +02:00
ulist.h btrfs: ulist: Add ulist_del() function. 2015-06-10 09:26:17 -07:00
uuid-tree.c Btrfs: make btrfs_search_forward return with nodes unlocked 2014-09-17 13:38:02 -07:00
volumes.c Merge branch 'cleanups-4.7' into for-chris-4.7-20160525 2016-05-25 22:51:03 +02:00
volumes.h Merge branch 'foreign/jeffm/uapi' into for-chris-4.7-20160516 2016-05-16 15:46:29 +02:00
xattr.c Btrfs: fix listxattrs not listing all xattrs packed in the same item 2016-03-01 08:23:41 -08:00
xattr.h btrfs: Use xattr handler infrastructure 2015-12-06 21:34:14 -05:00
zlib.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00