linux-toradex.git/include/linux/kernfs.h, branch v4.16-rc4

blktrace: add an option to allow displaying cgroup path

2017-07-29T15:00:03+00:00

By default we output cgroup id in blktrace. This adds an option to
display cgroup path. Since get cgroup path is a relativly heavy
operation, we don't enable it by default.

with the option enabled, blktrace will output something like this:
dd-1353  [007] d..2   293.015252:   8,0   /test/level  D   R 24 + 8 [dd]

Signed-off-by: Shaohua Li 
Signed-off-by: Jens Axboe

kernfs: add exportfs operations

2017-07-29T15:00:03+00:00

Now we have the facilities to implement exportfs operations. The idea is
cgroup can export the fhandle info to userspace, then userspace uses
fhandle to find the cgroup name. Another example is userspace can get
fhandle for a cgroup and BPF uses the fhandle to filter info for the
cgroup.

Acked-by: Greg Kroah-Hartman 
Signed-off-by: Shaohua Li 
Signed-off-by: Jens Axboe

kernfs: introduce kernfs_node_id

2017-07-29T15:00:03+00:00

inode number and generation can identify a kernfs node. We are going to
export the identification by exportfs operations, so put ino and
generation into a separate structure. It's convenient when later patches
use the identification.

Acked-by: Greg Kroah-Hartman 
Signed-off-by: Shaohua Li 
Signed-off-by: Jens Axboe

kernfs: implement i_generation

2017-07-29T15:00:03+00:00

Set i_generation for kernfs inode. This is required to implement
exportfs operations. The generation is 32-bit, so it's possible the
generation wraps up and we find stale files. To reduce the posssibility,
we don't reuse inode numer immediately. When the inode number allocation
wraps, we increase generation number. In this way generation/inode
number consist of a 64-bit number which is unlikely duplicated. This
does make the idr tree more sparse and waste some memory. Since idr
manages 32-bit keys, idr uses a 6-level radix tree, each level covers 6
bits of the key. In a 100k inode kernfs, the worst case will have around
300k radix tree node. Each node is 576bytes, so the tree will use about
~150M memory. Sounds not too bad, if this really is a problem, we should
find better data structure.

Acked-by: Tejun Heo 
Acked-by: Greg Kroah-Hartman 
Signed-off-by: Shaohua Li 
Signed-off-by: Jens Axboe

kernfs: use idr instead of ida to manage inode number

2017-07-29T15:00:03+00:00

kernfs uses ida to manage inode number. The problem is we can't get
kernfs_node from inode number with ida. Switching to use idr, next patch
will add an API to get kernfs_node from inode number.

Acked-by: Tejun Heo 
Acked-by: Greg Kroah-Hartman 
Signed-off-by: Shaohua Li 
Signed-off-by: Jens Axboe

kernfs: add kernfs_ops->open/release() callbacks

2016-12-27T19:49:03+00:00

Add ->open/release() methods to kernfs_ops.  ->open() is called when
the file is opened and ->release() when the file is either released or
severed.  These callbacks can be used, for example, to manage
persistent caching objects over multiple seq_file iterations.

Signed-off-by: Tejun Heo 
Acked-by: Greg Kroah-Hartman 
Acked-by: Acked-by: Zefan Li

kernfs: make kernfs_open_file->mmapped a bitfield

2016-12-27T19:49:02+00:00

More kernfs_open_file->mutex synchronized flags are planned to be
added.  Convert ->mmapped to a bitfield in preparation.

While at it, make kernfs_fop_mmap() use "true" instead of "1" on
->mmapped.

Signed-off-by: Tejun Heo 
Acked-by: Greg Kroah-Hartman 
Acked-by: Acked-by: Zefan Li

kernfs: remove kernfs_path_len()

2016-08-10T15:23:44+00:00

It doesn't have any in-kernel user and the same result can be obtained
from kernfs_path(@kn, NULL, 0).  Remove it.

Signed-off-by: Tejun Heo 
Acked-by: Greg Kroah-Hartman 
Cc: Serge Hallyn

kernfs: make kernfs_path*() behave in the style of strlcpy()

2016-08-10T15:23:44+00:00

kernfs_path*() functions always return the length of the full path but
the path content is undefined if the length is larger than the
provided buffer.  This makes its behavior different from strlcpy() and
requires error handling in all its users even when they don't care
about truncation.  In addition, the implementation can actully be
simplified by making it behave properly in strlcpy() style.

* Update kernfs_path_from_node_locked() to always fill up the buffer
  with path.  If the buffer is not large enough, the output is
  truncated and terminated.

* kernfs_path() no longer needs error handling.  Make it a simple
  inline wrapper around kernfs_path_from_node().

* sysfs_warn_dup()'s use of kernfs_path() doesn't need error handling.
  Updated accordingly.

* cgroup_path()'s use of kernfs_path() updated to retain the old
  behavior.

Signed-off-by: Tejun Heo 
Acked-by: Greg Kroah-Hartman 
Acked-by: Serge Hallyn

kernfs: add dummy implementation of kernfs_path_from_node()

2016-08-10T15:23:43+00:00

The dummy version of kernfs_path_from_node() was missing.  This
currently doesn't break anything.  Let's add it for consistency and to
ease adding wrappers around it.

v2: Removed stray ';' which was causing build failures.

Signed-off-by: Tejun Heo 
Acked-by: Greg Kroah-Hartman