linux.git/fs/btrfs/rcu-string.h, branch master

btrfs: remove struct rcu_string

2025-07-21T22:09:21+00:00

The only use for device name has been removed so we can kill the RCU
string API.

Reviewed-by: Daniel Vacek 
Signed-off-by: David Sterba

btrfs: remove unused rcu-string printk helpers

2025-07-21T21:56:38+00:00

The RCU-string API has never taken off and we don't use the printk
helpers provided as we do the protection in our helpers. Remove the "in
RCU" wrappers.

Reviewed-by: Daniel Vacek 
Signed-off-by: David Sterba

btrfs: open code rcu_string_free() and remove it

2025-07-21T21:56:38+00:00

The helper is trivial and we can simply use kfree_rcu() if needed. In
our case it's just one place where we rename a device in
device_list_add() and the old name can still be used until the end of
the RCU grace period. The other case is freeing a device and there
nothing should reach the device, so we can use plain kfree().

Reviewed-by: Daniel Vacek 
Signed-off-by: David Sterba

btrfs: add forward declarations and headers, part 1

2024-03-04T15:24:49+00:00

Do a cleanup in the short headers:

- add forward declarations for types referenced by pointers
- add includes when types need them

This fixes potential compilation problems if the headers are reordered
or the missing includes are not provided indirectly.

Signed-off-by: David Sterba

btrfs: replace strncpy() with strscpy()

2022-12-05T17:00:59+00:00

Using strncpy() on NUL-terminated strings are deprecated.  To avoid
possible forming of non-terminated string strscpy() should be used.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

CC: stable@vger.kernel.org # 4.9+
Signed-off-by: Artem Chernyshev 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: rcu-string: Replace zero-length array with flexible-array member

2020-03-23T16:01:53+00:00

The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array
member[1][2], introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning in
case the flexible array does not occur last in the structure, which will
help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by this
change:

 "Flexible array members have incomplete type, and so the sizeof operator
  may not be applied. As a quirk of the original implementation of
  zero-length arrays, sizeof evaluates to zero." [1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: replace GPL boilerplate by SPDX -- headers

2018-04-12T14:29:46+00:00

Remove GPL boilerplate text (long, short, one-line) and keep the rest,
ie. personal, company or original source copyright statements. Add the
SPDX header.

Unify the include protection macros to match the file names.

Signed-off-by: David Sterba

Btrfs: use rcu to protect device->name

2012-06-15T01:29:16+00:00

Al pointed out that we can just toss out the old name on a device and add a
new one arbitrarily, so anybody who uses device->name in printk could
possibly use free'd memory.  Instead of adding locking around all of this he
suggested doing it with RCU, so I've introduced a struct rcu_string that
does just that and have gone through and protected all accesses to
device->name that aren't under the uuid_mutex with rcu_read_lock().  This
protects us and I will use it for dealing with removing the device that we
used to mount the file system in a later patch.  Thanks,

Reviewed-by: David Sterba 
Signed-off-by: Josef Bacik