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procfs/dmabuf: add inode number to /proc/*/fdinfo

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And 'ino' field to /proc/<pid>/fdinfo/<FD> and
/proc/<pid>/task/<tid>/fdinfo/<FD>.

The inode numbers can be used to uniquely identify DMA buffers in user
space and avoids a dependency on /proc/<pid>/fd/* when accounting
per-process DMA buffer sizes.

Link: https://lkml.kernel.org/r/20210308170651.919148-2-kaleshsingh@google.com
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Christian König <christian.koenig@amd.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jeff Vander Stoep <jeffv@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Hridya Valsaraju <hridya@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Alexey Gladkov <gladkov.alexey@gmail.com>
Cc: Szabolcs Nagy <szabolcs.nagy@arm.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Bernd Edlinger <bernd.edlinger@hotmail.de>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Helge Deller <deller@gmx.de>
Cc: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kalesh Singh 2021-06-30 18:54:49 -07:00 committed by Linus Torvalds
parent 7bc3fa0172
commit 3845f256a8
2 changed files with 34 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

37
Documentation/filesystems/proc.rst
View File

@ -1920,18 +1920,20 @@ if precise results are needed.
3.8 /proc/<pid>/fdinfo/<fd> - Information about opened file
---------------------------------------------------------------
This file provides information associated with an opened file. The regular
files have at least three fields -- 'pos', 'flags' and 'mnt_id'. The 'pos'
represents the current offset of the opened file in decimal form [see lseek(2)
for details], 'flags' denotes the octal O_xxx mask the file has been
created with [see open(2) for details] and 'mnt_id' represents mount ID of
the file system containing the opened file [see 3.5 /proc/<pid>/mountinfo
for details].
files have at least four fields -- 'pos', 'flags', 'mnt_id' and 'ino'.
The 'pos' represents the current offset of the opened file in decimal
form [see lseek(2) for details], 'flags' denotes the octal O_xxx mask the
file has been created with [see open(2) for details] and 'mnt_id' represents
mount ID of the file system containing the opened file [see 3.5
/proc/<pid>/mountinfo for details]. 'ino' represents the inode number of
the file.
A typical output is::
pos: 0
flags: 0100002
mnt_id: 19
ino: 63107
All locks associated with a file descriptor are shown in its fdinfo too::
@ -1948,6 +1950,7 @@ Eventfd files
pos: 0
flags: 04002
mnt_id: 9
ino: 63107
eventfd-count: 5a
where 'eventfd-count' is hex value of a counter.
@ -1960,6 +1963,7 @@ Signalfd files
pos: 0
flags: 04002
mnt_id: 9
ino: 63107
sigmask: 0000000000000200
where 'sigmask' is hex value of the signal mask associated
@ -1973,6 +1977,7 @@ Epoll files
pos: 0
flags: 02
mnt_id: 9
ino: 63107
tfd: 5 events: 1d data: ffffffffffffffff pos:0 ino:61af sdev:7
where 'tfd' is a target file descriptor number in decimal form,
@ -1989,6 +1994,8 @@ For inotify files the format is the following::
pos: 0
flags: 02000000
mnt_id: 9
ino: 63107
inotify wd:3 ino:9e7e sdev:800013 mask:800afce ignored_mask:0 fhandle-bytes:8 fhandle-type:1 f_handle:7e9e0000640d1b6d
where 'wd' is a watch descriptor in decimal form, i.e. a target file
@ -2011,6 +2018,7 @@ For fanotify files the format is::
pos: 0
flags: 02
mnt_id: 9
ino: 63107
fanotify flags:10 event-flags:0
fanotify mnt_id:12 mflags:40 mask:38 ignored_mask:40000003
fanotify ino:4f969 sdev:800013 mflags:0 mask:3b ignored_mask:40000000 fhandle-bytes:8 fhandle-type:1 f_handle:69f90400c275b5b4
@ -2035,6 +2043,7 @@ Timerfd files
pos: 0
flags: 02
mnt_id: 9
ino: 63107
clockid: 0
ticks: 0
settime flags: 01
@ -2049,6 +2058,22 @@ details]. 'it_value' is remaining time until the timer expiration.
with TIMER_ABSTIME option which will be shown in 'settime flags', but 'it_value'
still exhibits timer's remaining time.
DMA Buffer files
~~~~~~~~~~~~~~~~
::
pos: 0
flags: 04002
mnt_id: 9
ino: 63107
size: 32768
count: 2
exp_name: system-heap
where 'size' is the size of the DMA buffer in bytes. 'count' is the file count of
the DMA buffer file. 'exp_name' is the name of the DMA buffer exporter.
3.9 /proc/<pid>/map_files - Information about memory mapped files
---------------------------------------------------------------------
This directory contains symbolic links which represent memory mapped files

5
fs/proc/fd.c
View File

@ -54,9 +54,10 @@ static int seq_show(struct seq_file *m, void *v)
if (ret)
return ret;
seq_printf(m, "pos:\t%lli\nflags:\t0%o\nmnt_id:\t%i\n",
seq_printf(m, "pos:\t%lli\nflags:\t0%o\nmnt_id:\t%i\nino:\t%lu\n",
(long long)file->f_pos, f_flags,
real_mount(file->f_path.mnt)->mnt_id);
real_mount(file->f_path.mnt)->mnt_id,
file_inode(file)->i_ino);
/* show_fd_locks() never deferences files so a stale value is safe */
show_fd_locks(m, file, files);