linux.git/fs/btrfs/export.c, branch v5.8

btrfs: simplify iget helpers

2020-05-25T09:25:37+00:00

The inode lookup starting at btrfs_iget takes the full location key,
while only the objectid is used to match the inode, because the lookup
happens inside the given root thus the inode number is unique.
The entire location key is properly set up in btrfs_init_locked_inode.

Simplify the helpers and pass only inode number, renaming it to 'ino'
instead of 'objectid'. This allows to remove temporary variables key,
saving some stack space.

Signed-off-by: David Sterba

btrfs: simplify root lookup by id

2020-05-25T09:25:36+00:00

The main function to lookup a root by its id btrfs_get_fs_root takes the
whole key, while only using the objectid. The value of offset is preset
to (u64)-1 but not actually used until btrfs_find_root that does the
actual search.

Switch btrfs_get_fs_root to use only objectid and remove all local
variables that existed just for the lookup. The actual key for search is
set up in btrfs_get_fs_root, reusing another key variable.

Signed-off-by: David Sterba

btrfs: kill the subvol_srcu

2020-03-23T16:02:00+00:00

Now that we have proper root ref counting everywhere we can kill the
subvol_srcu.

* removal of fs_info::subvol_srcu reduces size of fs_info by 1176 bytes

* the refcount_t used for the references checks for accidental 0->1
  in cases where the root lifetime would not be properly protected

* there's a leak detector for roots to catch unfreed roots at umount
  time

* SRCU served us well over the years but is was not a proper
  synchronization mechanism for some cases

Signed-off-by: Josef Bacik 
Reviewed-by: David Sterba 
[ update changelog ]
Signed-off-by: David Sterba

btrfs: export helpers for subvolume name/id resolution

2020-03-23T16:01:42+00:00

The functions will be used outside of export.c and super.c to allow
resolving subvolume name from a given id, eg. for subvolume deletion by
id ioctl.

Signed-off-by: Marcos Paulo de Souza 
Reviewed-by: David Sterba 
[ split from the next patch ]
Signed-off-by: David Sterba

btrfs: rename btrfs_put_fs_root and btrfs_grab_fs_root

2020-03-23T16:01:33+00:00

We are now using these for all roots, rename them to btrfs_put_root()
and btrfs_grab_root();

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

btrfs: push btrfs_grab_fs_root into btrfs_get_fs_root

2020-03-23T16:01:32+00:00

Now that all callers of btrfs_get_fs_root are subsequently calling
btrfs_grab_fs_root and handling dropping the ref when they are done
appropriately, go ahead and push btrfs_grab_fs_root up into
btrfs_get_fs_root.

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

btrfs: hold a root ref in btrfs_get_dentry

2020-03-23T16:01:27+00:00

Looking up the inode we need to search the root, make sure we hold a
reference on that root while we're doing the lookup.

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

btrfs: open code btrfs_read_fs_root_no_name

2020-03-23T16:01:26+00:00

All this does is call btrfs_get_fs_root() with check_ref == true.  Just
use btrfs_get_fs_root() so we don't have a bunch of different helpers
that do the same thing.

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

btrfs: drop unused parameter is_new from btrfs_iget

2019-11-18T11:46:52+00:00

The parameter is now always set to NULL and could be dropped. The last
user was get_default_root but that got reworked in 05dbe6837b60 ("Btrfs:
unify subvol= and subvolid= mounting") and the parameter became unused.

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

btrfs: Remove 'objectid' member from struct btrfs_root

2018-10-15T15:23:25+00:00

There are two members in struct btrfs_root which indicate root's
objectid: objectid and root_key.objectid.

They are both set to the same value in __setup_root():

  static void __setup_root(struct btrfs_root *root,
                           struct btrfs_fs_info *fs_info,
                           u64 objectid)
  {
    ...
    root->objectid = objectid;
    ...
    root->root_key.objectid = objecitd;
    ...
  }

and not changed to other value after initialization.

grep in btrfs directory shows both are used in many places:
  $ grep -rI "root->root_key.objectid" | wc -l
  133
  $ grep -rI "root->objectid" | wc -l
  55
 (4.17, inc. some noise)

It is confusing to have two similar variable names and it seems
that there is no rule about which should be used in a certain case.

Since ->root_key itself is needed for tree reloc tree, let's remove
'objecitd' member and unify code to use ->root_key.objectid in all places.

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