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author | Al Viro <viro@zeniv.linux.org.uk> | 2018-10-10 16:52:37 -0400 |
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committer | Al Viro <viro@zeniv.linux.org.uk> | 2018-10-10 16:52:37 -0400 |
commit | 1a16dbaf798c5b68ac767444eb045e6f3adaa16d (patch) | |
tree | a3e9365becacb65cd1fc6236170665f65196324b /Documentation/filesystems/porting | |
parent | 3837d208d8fe7437475c4a1c53fa5e517b16ceb0 (diff) | |
download | blackbird-obmc-linux-1a16dbaf798c5b68ac767444eb045e6f3adaa16d.tar.gz blackbird-obmc-linux-1a16dbaf798c5b68ac767444eb045e6f3adaa16d.zip |
Document d_splice_alias() calling conventions for ->lookup() users.
Short version: it does the right thing when given NULL or ERR_PTR(...)
and its calling conventions are chosen to have minimal PITA when
used in ->lookup() instances.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'Documentation/filesystems/porting')
-rw-r--r-- | Documentation/filesystems/porting | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting index 7b7b845c490a..321d74b73937 100644 --- a/Documentation/filesystems/porting +++ b/Documentation/filesystems/porting @@ -622,3 +622,14 @@ in your dentry operations instead. alloc_file_clone(file, flags, ops) does not affect any caller's references. On success you get a new struct file sharing the mount/dentry with the original, on failure - ERR_PTR(). +-- +[recommended] + ->lookup() instances doing an equivalent of + if (IS_ERR(inode)) + return ERR_CAST(inode); + return d_splice_alias(inode, dentry); + don't need to bother with the check - d_splice_alias() will do the + right thing when given ERR_PTR(...) as inode. Moreover, passing NULL + inode to d_splice_alias() will also do the right thing (equivalent of + d_add(dentry, NULL); return NULL;), so that kind of special cases + also doesn't need a separate treatment. |