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6fc9e5866c
android_kernel_xiaomi_sm8450/fs/btrfs
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Filipe Manana 6fc9e5866c btrfs: fix race between swap file activation and snapshot creation 
commit dd0734f2a866f9d619d4abf97c3d71bcdee40ea9 upstream.

When creating a snapshot we check if the current number of swap files, in
the root, is non-zero, and if it is, we error out and warn that we can not
create the snapshot because there are active swap files.

However this is racy because when a task started activation of a swap
file, another task might have started already snapshot creation and might
have seen the counter for the number of swap files as zero. This means
that after the swap file is activated we may end up with a snapshot of the
same root successfully created, and therefore when the first write to the
swap file happens it has to fall back into COW mode, which should never
happen for active swap files.

Basically what can happen is:

1) Task A starts snapshot creation and enters ioctl.c:create_snapshot().
   There it sees that root->nr_swapfiles has a value of 0 so it continues;

2) Task B enters btrfs_swap_activate(). It is not aware that another task
   started snapshot creation but it did not finish yet. It increments
   root->nr_swapfiles from 0 to 1;

3) Task B checks that the file meets all requirements to be an active
   swap file - it has NOCOW set, there are no snapshots for the inode's
   root at the moment, no file holes, no reflinked extents, etc;

4) Task B returns success and now the file is an active swap file;

5) Task A commits the transaction to create the snapshot and finishes.
   The swap file's extents are now shared between the original root and
   the snapshot;

6) A write into an extent of the swap file is attempted - there is a
   snapshot of the file's root, so we fall back to COW mode and therefore
   the physical location of the extent changes on disk.

So fix this by taking the snapshot lock during swap file activation before
locking the extent range, as that is the order in which we lock these
during buffered writes.

Fixes: ed46ff3d42 ("Btrfs: support swap files")
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-09 11:11:11 +01:00
..
tests btrfs: fix missing delalloc new bit for new delalloc ranges 2020-11-13 22:15:59 +01:00
acl.c btrfs: cleanup btrfs_setxattr_trans and drop transaction parameter 2019-04-29 19:02:44 +02:00
async-thread.c Btrfs: fix crash during unmount due to race with delayed inode workers 2020-03-23 17:01:51 +01:00
async-thread.h Btrfs: fix crash during unmount due to race with delayed inode workers 2020-03-23 17:01:51 +01:00
backref.c btrfs: do not warn if we can't find the reloc root when looking up backref 2021-03-04 11:38:29 +01:00
backref.h btrfs: add asserts for deleting backref cache nodes 2021-03-04 11:38:29 +01:00
block-group.c btrfs: fix race between writes to swap files and scrub 2021-03-09 11:11:11 +01:00
block-group.h btrfs: fix race between writes to swap files and scrub 2021-03-09 11:11:11 +01:00
block-rsv.c btrfs: print the block rsv type when we fail our reservation 2020-11-05 13:02:05 +01:00
block-rsv.h btrfs: Remove __ prefix from btrfs_block_rsv_release 2020-03-23 17:01:55 +01:00
btrfs_inode.h btrfs: fix deadlock when cloning inline extent and low on free metadata space 2021-01-17 14:16:54 +01:00
check-integrity.c btrfs: check-integrity: remove unnecessary failure messages during memory allocation 2020-07-27 12:55:21 +02:00
check-integrity.h btrfs: remove btrfsic_submit_bh() 2020-03-23 17:01:39 +01:00
compression.c btrfs: compression: move declarations to header 2020-10-07 12:06:55 +02:00
compression.h btrfs: compression: move declarations to header 2020-10-07 12:06:55 +02:00
ctree.c btrfs: fix extent buffer leak on failure to copy root 2021-03-04 11:38:30 +01:00
ctree.h btrfs: fix race between writes to swap files and scrub 2021-03-09 11:11:11 +01:00
delalloc-space.c btrfs: add btrfs_reserve_data_bytes and use it 2020-10-07 12:06:52 +02:00
delalloc-space.h btrfs: make btrfs_delalloc_reserve_space take btrfs_inode 2020-07-27 12:55:36 +02:00
delayed-inode.c btrfs: sink total_data parameter in setup_items_for_insert 2020-10-07 12:13:18 +02:00
delayed-inode.h btrfs: delayed-inode: Replace zero-length array with flexible-array member 2020-03-23 17:01:53 +01:00
delayed-ref.c btrfs: account for new extents being deleted in total_bytes_pinned 2021-03-04 11:38:30 +01:00
delayed-ref.h btrfs: handle space_info::total_bytes_pinned inside the delayed ref itself 2021-03-04 11:38:30 +01:00
dev-replace.c btrfs: fix deadlock when cloning inline extent and low on free metadata space 2021-01-17 14:16:54 +01:00
dev-replace.h btrfs: add __pure attribute to functions 2019-11-18 12:46:52 +01:00
dir-item.c btrfs: remove unused parameter fs_info from btrfs_extend_item 2019-04-29 19:02:50 +02:00
discard.c btrfs: merge critical sections of discard lock in workfn 2021-01-19 18:27:24 +01:00
discard.h btrfs: discard: Use the correct style for SPDX License Identifier 2020-04-20 17:43:42 +02:00
disk-io.c btrfs: print the actual offset in btrfs_root_name 2021-01-27 11:55:06 +01:00
disk-io.h btrfs: add a helper to read the tree_root commit root for backref lookup 2020-10-26 15:04:57 +01:00
export.c btrfs: simplify iget helpers 2020-05-25 11:25:37 +02:00
export.h btrfs: export helpers for subvolume name/id resolution 2020-03-23 17:01:42 +01:00
extent_io.c btrfs: prevent NULL pointer dereference in extent_io_tree_panic 2021-01-19 18:27:17 +01:00
extent_io.h btrfs: remove struct extent_io_ops 2020-10-07 12:13:25 +02:00
extent_map.c Btrfs: fix race between using extent maps and merging them 2020-02-12 17:16:46 +01:00
extent_map.h btrfs: remove extent_map::bdev 2019-11-18 23:43:44 +01:00
extent-io-tree.h btrfs: remove struct extent_io_ops 2020-10-07 12:13:25 +02:00
extent-tree.c btrfs: account for new extents being deleted in total_bytes_pinned 2021-03-04 11:38:30 +01:00
file-item.c btrfs: make btrfs_find_ordered_sum take btrfs_inode 2020-10-07 12:12:19 +02:00
file.c btrfs: fix missing delalloc new bit for new delalloc ranges 2020-11-13 22:15:59 +01:00
free-space-cache.c btrfs: avoid double put of block group when emptying cluster 2021-03-09 11:11:10 +01:00
free-space-cache.h btrfs: let btrfs_return_cluster_to_free_space() return void 2020-07-27 12:55:21 +02:00
free-space-tree.c btrfs: fix possible free space tree corruption with online conversion 2021-02-03 23:28:40 +01:00
free-space-tree.h btrfs: rename btrfs_block_group_cache 2019-11-18 17:51:51 +01:00
inode-item.c btrfs: Make btrfs_find_name_in_ext_backref return struct btrfs_inode_extref 2019-09-09 14:59:16 +02:00
inode-map.c btrfs: make btrfs_delalloc_reserve_space take btrfs_inode 2020-07-27 12:55:36 +02:00
inode-map.h
inode.c btrfs: fix race between swap file activation and snapshot creation 2021-03-09 11:11:11 +01:00
ioctl.c btrfs: fix deadlock when cloning inline extent and low on free metadata space 2021-01-17 14:16:54 +01:00
Kconfig btrfs: switch to iomap for direct IO 2020-10-07 12:06:57 +02:00
locking.c btrfs: add nesting tags to the locking helpers 2020-10-07 12:12:16 +02:00
locking.h btrfs: introduce BTRFS_NESTING_NEW_ROOT for adding new roots 2020-10-07 12:12:17 +02:00
lzo.c btrfs: compression: inline free_workspace 2019-11-18 12:46:59 +01:00
Makefile Btrfs: move all reflink implementation code into its own file 2020-03-23 17:01:54 +01:00
misc.h btrfs: rename tree_entry to rb_simple_node and export it 2020-05-25 11:25:19 +02:00
ordered-data.c btrfs: remove inode argument from btrfs_start_ordered_extent 2020-10-07 12:13:22 +02:00
ordered-data.h btrfs: remove inode argument from btrfs_start_ordered_extent 2020-10-07 12:13:22 +02:00
orphan.c
print-tree.c btrfs: print the actual offset in btrfs_root_name 2021-01-27 11:55:06 +01:00
print-tree.h btrfs: print the actual offset in btrfs_root_name 2021-01-27 11:55:06 +01:00
props.c btrfs: simplify iget helpers 2020-05-25 11:25:37 +02:00
props.h btrfs: delete unused function btrfs_set_prop_trans 2019-04-29 19:02:54 +02:00
qgroup.c btrfs: fix transaction leak and crash after RO remount caused by qgroup rescan 2021-01-19 18:27:24 +01:00
qgroup.h btrfs: qgroup: export qgroups in sysfs 2020-07-27 12:55:37 +02:00
raid56.c btrfs: fix raid6 qstripe kmap 2021-03-09 11:11:10 +01:00
raid56.h btrfs: constify map parameter for nr_parity_stripes and nr_data_stripes 2019-07-01 13:34:58 +02:00
rcu-string.h btrfs: rcu-string: Replace zero-length array with flexible-array member 2020-03-23 17:01:53 +01:00
reada.c btrfs: fix readahead hang and use-after-free after removing a device 2020-10-26 15:03:59 +01:00
ref-verify.c btrfs: ref-verify: fix memory leak in btrfs_ref_tree_mod 2020-11-05 13:03:39 +01:00
ref-verify.h btrfs: ref-verify: Use btrfs_ref to refactor btrfs_ref_tree_mod() 2019-04-29 19:02:49 +02:00
reflink.c btrfs: fix deadlock when cloning inline extent and low on free metadata space 2021-01-17 14:16:54 +01:00
reflink.h Btrfs: move all reflink implementation code into its own file 2020-03-23 17:01:54 +01:00
relocation.c btrfs: fix reloc root leak with 0 ref reloc roots on recovery 2021-03-04 11:38:30 +01:00
root-tree.c btrfs: qgroup: fix qgroup meta rsv leak for subvolume operations 2020-10-07 12:12:13 +02:00
scrub.c btrfs: fix race between writes to swap files and scrub 2021-03-09 11:11:11 +01:00
send.c btrfs: send: fix invalid clone operations when cloning from the same file and root 2021-01-27 11:54:53 +01:00
send.h btrfs: send: avoid copying file data 2020-10-07 12:13:17 +02:00
space-info.c btrfs: shrink delalloc pages instead of full inodes 2021-01-17 14:16:54 +01:00
space-info.h btrfs: handle space_info::total_bytes_pinned inside the delayed ref itself 2021-03-04 11:38:30 +01:00
struct-funcs.c btrfs: use unaligned helpers for stack and header set/get helpers 2020-10-07 12:13:23 +02:00
super.c btrfs: fix transaction leak and crash after RO remount caused by qgroup rescan 2021-01-19 18:27:24 +01:00
sysfs.c btrfs: do not create raid sysfs entries under any locks 2020-10-07 12:13:19 +02:00
sysfs.h btrfs: split and refactor btrfs_sysfs_remove_devices_dir 2020-10-07 12:12:21 +02:00
transaction.c btrfs: fix error handling in commit_fs_roots 2021-03-07 12:34:13 +01:00
transaction.h btrfs: dio iomap DSYNC workaround 2020-10-07 12:06:57 +02:00
tree-checker.c btrfs: tree-checker: check if chunk item end overflows 2021-01-19 18:27:22 +01:00
tree-checker.h btrfs: get fs_info from eb in btrfs_check_chunk_valid 2019-04-29 19:02:39 +02:00
tree-defrag.c btrfs: remove unused btrfs_root::defrag_trans_start 2020-07-27 12:55:28 +02:00
tree-log.c btrfs: skip unnecessary searches for xattrs when logging an inode 2021-01-17 14:16:53 +01:00
tree-log.h btrfs: make fast fsyncs wait only for writeback 2020-10-07 12:06:56 +02:00
ulist.c
ulist.h
uuid-tree.c btrfs: simplify root lookup by id 2020-05-25 11:25:36 +02:00
volumes.c btrfs: fix lockdep warning due to seqcount_mutex on 32bit arch 2021-02-03 23:28:40 +01:00
volumes.h btrfs: fix lockdep warning due to seqcount_mutex on 32bit arch 2021-02-03 23:28:40 +01:00
xattr.c btrfs: skip unnecessary searches for xattrs when logging an inode 2021-01-17 14:16:53 +01:00
xattr.h btrfs: cleanup btrfs_setxattr_trans and drop transaction parameter 2019-04-29 19:02:44 +02:00
zlib.c btrfs: use larger zlib buffer for s390 hardware compression 2020-01-31 10:30:40 -08:00
zstd.c btrfs: compression: inline free_workspace 2019-11-18 12:46:59 +01:00