linux.git/fs/btrfs/locking.c, branch v6.9

btrfs: change BUG_ON to assertion when verifying lockdep class setup

2024-03-04T15:24:48+00:00

The BUG_ON in btrfs_set_buffer_lockdep_class() is a sanity check of the
level which is verified in callers, e.g. when initializing an extent
buffer or reading from an eb header. Change it to an assertion as this
would not happen unless things are really bad and would fail elsewhere
too.

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

btrfs: remove unused included headers

2024-03-04T15:24:46+00:00

With help of neovim, LSP and clangd we can identify header files that
are not actually needed to be included in the .c files. This is focused
only on removal (with minor fixups), further cleanups are possible but
will require doing the header files properly with forward declarations,
minimized includes and include-what-you-use care.

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

btrfs: add raid stripe tree definitions

2023-10-12T14:44:09+00:00

Add definitions for the raid stripe tree. This tree will hold information
about the on-disk layout of the stripes in a RAID set.

Each stripe extent has a 1:1 relationship with an on-disk extent item and
is doing the logical to per-drive physical address translation for the
extent item in question.

Signed-off-by: Johannes Thumshirn 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: move extent_buffer::lock_owner to debug section

2023-10-12T14:44:05+00:00

The lock_owner is used for a rare corruption case and we haven't seen
any reports in years. Move it to the debugging section of eb.  To close
the holes also move log_index so the final layout looks like:

struct extent_buffer {
        u64                        start;                /*     0     8 */
        long unsigned int          len;                  /*     8     8 */
        long unsigned int          bflags;               /*    16     8 */
        struct btrfs_fs_info *     fs_info;              /*    24     8 */
        spinlock_t                 refs_lock;            /*    32     4 */
        atomic_t                   refs;                 /*    36     4 */
        int                        read_mirror;          /*    40     4 */
        s8                         log_index;            /*    44     1 */

        /* XXX 3 bytes hole, try to pack */

        struct callback_head       callback_head __attribute__((__aligned__(8))); /*    48    16 */
        /* --- cacheline 1 boundary (64 bytes) --- */
        struct rw_semaphore        lock;                 /*    64    40 */
        struct page *              pages[16];            /*   104   128 */

        /* size: 232, cachelines: 4, members: 11 */
        /* sum members: 229, holes: 1, sum holes: 3 */
        /* forced alignments: 1, forced holes: 1, sum forced holes: 3 */
        /* last cacheline: 40 bytes */
} __attribute__((__aligned__(8)));

This saves 8 bytes in total and still keeps the lock on a separate cacheline.

Reviewed-by: Qu Wenruo 
Signed-off-by: David Sterba

btrfs: reformat remaining kdoc style comments

2023-10-12T14:44:04+00:00

Function name in the comment does not bring much value to code not
exposed as API and we don't stick to the kdoc format anymore. Update
formatting of parameter descriptions.

Reviewed-by: Qu Wenruo 
Signed-off-by: David Sterba

btrfs: include trace header in where necessary

2023-10-12T14:44:03+00:00

If we no longer include the tracepoints from ctree.h we fail to compile
because we have the dependency in some of the header files and source
files.  Add the include where we have these dependencies to allow us to
remove the include from ctree.h.

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

btrfs: add block-group tree to lockdep classes

2023-06-19T11:59:35+00:00

The block group tree was not present among the lockdep classes. We could
get potentially lockdep warnings but so far none has been seen, also
because block-group-tree is a relatively new feature.

CC: stable@vger.kernel.org # 6.1+
Signed-off-by: David Sterba

btrfs: locking: use atomic for DREW lock writers

2023-04-17T16:01:17+00:00

The DREW lock uses percpu variable to track lock counters and for that
it needs to allocate the structure. In btrfs_read_tree_root() or
btrfs_init_fs_root() this may add another error case or requires the
NOFS scope protection.

One way is to preallocate the structure as was suggested in
https://lore.kernel.org/linux-btrfs/20221214021125.28289-1-robbieko@synology.com/

We may avoid the allocation altogether if we don't use the percpu
variables but an atomic for the writer counter. This should not make any
difference, the DREW lock is used for truncate and NOCOW writes along
with other IO operations.

The percpu counter for writers has been there since the original commit
8257b2dc3c1a1057 "Btrfs: introduce btrfs_{start, end}_nocow_write() for
each subvolume". The reason could be to avoid hammering the same
cacheline from all the readers but then the writers do that anyway.

Signed-off-by: David Sterba

btrfs: move accessor helpers into accessors.h

2022-12-05T17:00:42+00:00

This is a large patch, but because they're all macros it's impossible to
split up.  Simply copy all of the item accessors in ctree.h and paste
them in accessors.h, and then update any files to include the header so
everything compiles.

Reviewed-by: Anand Jain 
Signed-off-by: Josef Bacik 
Reviewed-by: David Sterba 
[ reformat comments, style fixups ]
Signed-off-by: David Sterba

btrfs: implement a nowait option for tree searches

2022-09-26T10:46:42+00:00

For NOWAIT IOCBs we'll need a way to tell search to not wait on locks
or anything.  Accomplish this by adding a path->nowait flag that will
use trylocks and skip reading of metadata, returning -EAGAIN in either
of these cases.  For now we only need this for reads, so only the read
side is handled.  Add an ASSERT() to catch anybody trying to use this
for writes so they know they'll have to implement the write side.

Reviewed-by: Filipe Manana 
Signed-off-by: Josef Bacik 
Signed-off-by: Stefan Roesch 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba