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author | Al Viro <viro@zeniv.linux.org.uk> | 2015-05-11 08:29:30 -0400 |
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committer | Al Viro <viro@zeniv.linux.org.uk> | 2015-05-15 01:10:36 -0400 |
commit | 203bc643db59e2538e9a3f19be1636cdfd2bb2db (patch) | |
tree | 370610d82cc68a796c8a48eda8b70ba1171039d5 | |
parent | 8f47a0167c567de4ef552e26101b4f54a9b8ad48 (diff) | |
download | op-kernel-dev-203bc643db59e2538e9a3f19be1636cdfd2bb2db.zip op-kernel-dev-203bc643db59e2538e9a3f19be1636cdfd2bb2db.tar.gz |
update Documentation/filesystems/ regarding the follow_link/put_link changes
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r-- | Documentation/filesystems/porting | 17 | ||||
-rw-r--r-- | Documentation/filesystems/vfs.txt | 18 |
2 files changed, 27 insertions, 8 deletions
diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting index e69274d..3eae250 100644 --- a/Documentation/filesystems/porting +++ b/Documentation/filesystems/porting @@ -483,3 +483,20 @@ in your dentry operations instead. -- [mandatory] ->aio_read/->aio_write are gone. Use ->read_iter/->write_iter. +--- +[recommended] + for embedded ("fast") symlinks just set inode->i_link to wherever the + symlink body is and use simple_follow_link() as ->follow_link(). +-- +[mandatory] + calling conventions for ->follow_link() have changed. Instead of returning + cookie and using nd_set_link() to store the body to traverse, we return + the body to traverse and store the cookie using explicit void ** argument. + nameidata isn't passed at all - nd_jump_link() doesn't need it and + nd_[gs]et_link() is gone. +-- +[mandatory] + calling conventions for ->put_link() have changed. It gets inode instead of + dentry, it does not get nameidata at all and it gets called only when cookie + is non-NULL. Note that link body isn't available anymore, so if you need it, + store it as cookie. diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index 542d935..b403b29e 100644 --- a/Documentation/filesystems/vfs.txt +++ b/Documentation/filesystems/vfs.txt @@ -436,16 +436,18 @@ otherwise noted. follow_link: called by the VFS to follow a symbolic link to the inode it points to. Only required if you want to support - symbolic links. This method returns a void pointer cookie - that is passed to put_link(). + symbolic links. This method returns the symlink body + to traverse (and possibly resets the current position with + nd_jump_link()). If the body won't go away until the inode + is gone, nothing else is needed; if it needs to be otherwise + pinned, the data needed to release whatever we'd grabbed + is to be stored in void * variable passed by address to + follow_link() instance. put_link: called by the VFS to release resources allocated by - follow_link(). The cookie returned by follow_link() is passed - to this method as the last parameter. It is used by - filesystems such as NFS where page cache is not stable - (i.e. page that was installed when the symbolic link walk - started might not be in the page cache at the end of the - walk). + follow_link(). The cookie stored by follow_link() is passed + to this method as the last parameter; only called when + cookie isn't NULL. permission: called by the VFS to check for access rights on a POSIX-like filesystem. |