linux/fs
Filipe Manana 4a4f8fe2b0 btrfs: add and use helpers for reading and writing fs_info->generation
Currently the generation field of struct btrfs_fs_info is always modified
while holding fs_info->trans_lock locked. Most readers will access this
field without taking that lock but while holding a transaction handle,
which is safe to do due to the transaction life cycle.

However there are other readers that are neither holding the lock nor
holding a transaction handle open:

1) When reading an inode from disk, at btrfs_read_locked_inode();

2) When reading the generation to expose it to sysfs, at
   btrfs_generation_show();

3) Early in the fsync path, at skip_inode_logging();

4) When creating a hole at btrfs_cont_expand(), during write paths,
   truncate and reflinking;

5) In the fs_info ioctl (btrfs_ioctl_fs_info());

6) While mounting the filesystem, in the open_ctree() path. In these
   cases it's safe to directly read fs_info->generation as no one
   can concurrently start a transaction and update fs_info->generation.

In case of the fsync path, races here should be harmless, and in the worst
case they may cause a fsync to log an inode when it's not really needed,
so nothing bad from a functional perspective. In the other cases it's not
so clear if functional problems may arise, though in case 1 rare things
like a load/store tearing [1] may cause the BTRFS_INODE_NEEDS_FULL_SYNC
flag not being set on an inode and therefore result in incorrect logging
later on in case a fsync call is made.

To avoid data race warnings from tools like KCSAN and other issues such
as load and store tearing (amongst others, see [1]), create helpers to
access the generation field of struct btrfs_fs_info using READ_ONCE() and
WRITE_ONCE(), and use these helpers where needed.

[1] https://lwn.net/Articles/793253/

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-10-12 16:44:17 +02:00
..
9p - Some swap cleanups from Ma Wupeng ("fix WARN_ON in add_to_avail_list") 2023-08-29 14:25:26 -07:00
adfs for-6.6/block-2023-08-28 2023-08-29 20:21:42 -07:00
affs for-6.6/block-2023-08-28 2023-08-29 20:21:42 -07:00
afs - Some swap cleanups from Ma Wupeng ("fix WARN_ON in add_to_avail_list") 2023-08-29 14:25:26 -07:00
autofs v6.6-vfs.autofs 2023-08-28 11:39:14 -07:00
befs for-6.6/block-2023-08-28 2023-08-29 20:21:42 -07:00
bfs for-6.6/block-2023-08-28 2023-08-29 20:21:42 -07:00
btrfs btrfs: add and use helpers for reading and writing fs_info->generation 2023-10-12 16:44:17 +02:00
cachefiles - Some swap cleanups from Ma Wupeng ("fix WARN_ON in add_to_avail_list") 2023-08-29 14:25:26 -07:00
ceph ceph: remove unnecessary check for NULL in parse_longname() 2023-09-18 12:04:50 +02:00
coda v6.6-vfs.ctime 2023-08-28 09:31:32 -07:00
configfs configfs: convert to ctime accessor functions 2023-07-13 10:28:05 +02:00
cramfs v6.6-vfs.super 2023-08-28 11:04:18 -07:00
crypto
debugfs Char/Misc driver changes for 6.6-rc1 2023-09-01 09:53:54 -07:00
devpts v6.6-vfs.misc 2023-08-28 10:17:14 -07:00
dlm dlm: fix plock lookup when using multiple lockspaces 2023-08-25 10:31:39 -05:00
ecryptfs v6.6-vfs.misc 2023-08-28 10:17:14 -07:00
efivarfs efivarfs: fix statfs() on efivarfs 2023-09-11 09:10:02 +00:00
efs for-6.6/block-2023-08-28 2023-08-29 20:21:42 -07:00
erofs erofs: allow empty device tags in flatdev mode 2023-09-19 08:39:02 +08:00
exfat for-6.6/block-2023-08-28 2023-08-29 20:21:42 -07:00
exportfs exportfs: remove kernel-doc warnings in exportfs 2023-08-29 17:45:22 -04:00
ext2 \n 2023-08-30 12:10:50 -07:00
ext4 Revert "ext4: switch to multigrain timestamps" 2023-09-20 18:05:31 +02:00
f2fs f2fs update for 6.6-rc1 2023-09-02 15:37:59 -07:00
fat for-6.6/block-2023-08-28 2023-08-29 20:21:42 -07:00
freevxfs for-6.6/block-2023-08-28 2023-08-29 20:21:42 -07:00
fscache
fuse fuse update for 6.6 2023-09-05 12:45:55 -07:00
gfs2 gfs2: Fix quota=quiet oversight 2023-09-18 16:26:24 +02:00
hfs for-6.6/block-2023-08-28 2023-08-29 20:21:42 -07:00
hfsplus for-6.6/block-2023-08-28 2023-08-29 20:21:42 -07:00
hostfs hostfs: convert to ctime accessor functions 2023-07-24 10:30:00 +02:00
hpfs for-6.6/block-2023-08-28 2023-08-29 20:21:42 -07:00
hugetlbfs - Some swap cleanups from Ma Wupeng ("fix WARN_ON in add_to_avail_list") 2023-08-29 14:25:26 -07:00
iomap iomap: Spelling s/preceeding/preceding/g 2023-09-28 09:26:58 -07:00
isofs for-6.6/block-2023-08-28 2023-08-29 20:21:42 -07:00
jbd2 Regression and bug fixes for ext4. 2023-09-17 10:33:53 -07:00
jffs2 jffs2: convert to ctime accessor functions 2023-07-24 10:30:01 +02:00
jfs A few small fixes 2023-08-31 15:25:01 -07:00
kernfs Driver core changes for 6.6-rc1 2023-09-01 09:43:18 -07:00
lockd SUNRPC: Add enum svc_auth_status 2023-08-29 17:45:22 -04:00
minix for-6.6/block-2023-08-28 2023-08-29 20:21:42 -07:00
netfs netfs: Only call folio_start_fscache() one time for each folio 2023-09-18 12:03:46 -07:00
nfs nfs: decrement nrequests counter before releasing the req 2023-09-28 12:22:25 -04:00
nfs_common
nfsd nfsd-6.6 fixes: 2023-09-30 09:44:48 -07:00
nilfs2 nilfs2: fix potential use after free in nilfs_gccache_submit_read_data() 2023-09-29 17:20:46 -07:00
nls nls: Hide new NLS_UCS2_UTILS 2023-08-31 12:07:34 -05:00
notify dnotify: Pass argument of fcntl_dirnotify as int 2023-07-10 14:36:12 +02:00
ntfs for-6.6/block-2023-08-28 2023-08-29 20:21:42 -07:00
ntfs3 ntfs3: put resources during ntfs_fill_super() 2023-09-25 14:12:42 +02:00
ocfs2 Many ext4 and jbd2 cleanups and bug fixes for v6.6-rc1. 2023-08-31 15:18:15 -07:00
omfs for-6.6/block-2023-08-28 2023-08-29 20:21:42 -07:00
openpromfs openpromfs: convert to ctime accessor functions 2023-07-24 10:30:03 +02:00
orangefs fs: drop the timespec64 argument from update_time 2023-08-11 09:04:57 +02:00
overlayfs ovl: fix NULL pointer defer when encoding non-decodable lower fid 2023-10-03 09:24:11 +03:00
proc proc: nommu: fix empty /proc/<pid>/maps 2023-09-19 13:21:34 -07:00
pstore pstore fix for v6.6-rc1 2023-09-02 10:45:17 -07:00
qnx4 for-6.6/block-2023-08-28 2023-08-29 20:21:42 -07:00
qnx6 for-6.6/block-2023-08-28 2023-08-29 20:21:42 -07:00
quota quota: Fix slow quotaoff 2023-10-06 11:01:23 +02:00
ramfs ramfs: convert to ctime accessor functions 2023-07-24 10:30:04 +02:00
reiserfs reiserfs: Replace 1-element array with C99 style flex-array 2023-09-11 14:07:46 +02:00
romfs for-6.6/block-2023-08-28 2023-08-29 20:21:42 -07:00
smb Six SMB3 server fixes 2023-10-08 10:10:52 -07:00
squashfs squashfs: convert to ctime accessor functions 2023-07-24 10:30:05 +02:00
sysfs
sysv for-6.6/block-2023-08-28 2023-08-29 20:21:42 -07:00
tracefs eventfs: Test for dentries array allocated in eventfs_release() 2023-09-30 16:26:04 -04:00
ubifs fs: drop the timespec64 argument from update_time 2023-08-11 09:04:57 +02:00
udf \n 2023-08-30 12:10:50 -07:00
ufs for-6.6/block-2023-08-28 2023-08-29 20:21:42 -07:00
unicode
vboxsf v6.6-vfs.ctime 2023-08-28 09:31:32 -07:00
verity fsverity: skip PKCS#7 parser when keyring is empty 2023-08-20 10:33:43 -07:00
xfs xfs: abort fstrim if kernel is suspending 2023-10-04 09:25:04 +11:00
zonefs New code for 6.6: 2023-08-28 11:59:52 -07:00
aio.c aio: Annotate struct kioctx_table with __counted_by 2023-09-20 14:22:01 +02:00
anon_inodes.c
attr.c v6.6-vfs.misc 2023-08-28 10:17:14 -07:00
bad_inode.c fs: drop the timespec64 argument from update_time 2023-08-11 09:04:57 +02:00
binfmt_elf_fdpic.c fs: binfmt_elf_efpic: fix personality for ELF-FDPIC 2023-09-29 17:20:45 -07:00
binfmt_elf_test.c
binfmt_elf.c Merge branch 'expand-stack' 2023-06-28 20:35:21 -07:00
binfmt_flat.c
binfmt_misc.c fs: convert to ctime accessor functions 2023-07-13 10:28:04 +02:00
binfmt_script.c
buffer.c iomap: add a workaround for racy i_size updates on block devices 2023-09-25 08:55:00 -07:00
char_dev.c
compat_binfmt_elf.c
coredump.c v6.5/vfs.misc 2023-06-26 09:50:21 -07:00
d_path.c
dax.c mm: remove enum page_entry_size 2023-08-24 16:20:30 -07:00
dcache.c fs/dcache: Replace printk and WARN_ON by WARN 2023-08-19 13:41:11 +02:00
direct-io.c - Yosry Ahmed brought back some cgroup v1 stats in OOM logs. 2023-06-28 10:28:11 -07:00
drop_caches.c fs: drop_caches: draining pages before dropping caches 2023-08-18 10:12:11 -07:00
eventfd.c eventfd: prevent underflow for eventfd semaphores 2023-07-11 11:41:34 +02:00
eventpoll.c epoll: simplify ep_alloc() 2023-07-26 14:56:07 +02:00
exec.c - An extensive rework of kexec and crash Kconfig from Eric DeVolder 2023-08-29 14:53:51 -07:00
fcntl.c fcntl: Cast commands with int args explicitly 2023-07-10 14:36:11 +02:00
fhandle.c
file_table.c fs: use __fput_sync in close(2) 2023-08-08 19:36:51 +02:00
file.c v6.6-vfs.misc 2023-08-28 10:17:14 -07:00
filesystems.c
fs_context.c v6.6-vfs.misc 2023-08-28 10:17:14 -07:00
fs_parser.c
fs_pin.c
fs_struct.c kill do_each_thread() 2023-08-21 13:46:25 -07:00
fs_types.c
fs-writeback.c fs-writeback: do not requeue a clean inode having skipped pages 2023-09-20 14:22:01 +02:00
fsopen.c fs: add FSCONFIG_CMD_CREATE_EXCL 2023-08-14 18:48:02 +02:00
init.c
inode.c Revert "fs: add infrastructure for multigrain timestamps" 2023-09-20 18:05:31 +02:00
internal.h for-6.6/block-2023-08-28 2023-08-29 20:21:42 -07:00
ioctl.c v6.6-vfs.super 2023-08-28 11:04:18 -07:00
Kconfig for-6.6/block-2023-08-28 2023-08-29 20:21:42 -07:00
Kconfig.binfmt riscv: support the elf-fdpic binfmt loader 2023-08-23 14:17:43 -07:00
kernel_read_file.c fs: Fix kernel-doc warnings 2023-08-19 12:12:12 +02:00
libfs.c direct_write_fallback(): on error revert the ->ki_pos update from buffered write 2023-09-20 14:22:01 +02:00
locks.c NFSD 6.6 Release Notes 2023-08-31 15:32:18 -07:00
Makefile fs: add CONFIG_BUFFER_HEAD 2023-08-02 09:13:09 -06:00
mbcache.c
mnt_idmapping.c
mount.h
mpage.c
namei.c fs: Fix kernel-doc warnings 2023-08-19 12:12:12 +02:00
namespace.c v6.5/vfs.mount 2023-06-26 10:27:04 -07:00
nsfs.c fs: convert to ctime accessor functions 2023-07-13 10:28:04 +02:00
open.c v6.6-vfs.fchmodat2 2023-08-28 11:25:27 -07:00
pipe.c fs/pipe: remove duplicate "offset" initializer 2023-09-20 14:22:01 +02:00
pnode.c
pnode.h
posix_acl.c fs: convert to ctime accessor functions 2023-07-13 10:28:04 +02:00
proc_namespace.c
read_write.c fs: Fix one kernel-doc comment 2023-08-15 08:32:45 +02:00
readdir.c vfs: get rid of old '->iterate' directory operation 2023-08-06 15:08:35 +02:00
remap_range.c
select.c
seq_file.c
signalfd.c
splice.c - Some swap cleanups from Ma Wupeng ("fix WARN_ON in add_to_avail_list") 2023-08-29 14:25:26 -07:00
stack.c fs: convert to ctime accessor functions 2023-07-13 10:28:04 +02:00
stat.c Revert "fs: add infrastructure for multigrain timestamps" 2023-09-20 18:05:31 +02:00
statfs.c
super.c fs: export sget_dev() 2023-08-31 12:47:15 +02:00
sync.c
sysctls.c
timerfd.c
userfaultfd.c mm: userfaultfd: remove stale comment about core dump locking 2023-08-24 16:20:27 -07:00
utimes.c
xattr.c tmpfs,xattr: GFP_KERNEL_ACCOUNT for simple xattrs 2023-08-22 10:57:46 +02:00