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

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>

diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst
index dd4e3e18c22bcc0b169ead6e9bdac73e60f707f1..042c418f409067970a0f28ecc71505a77dcc454c 100644 (file)
--- a/Documentation/filesystems/proc.rst
+++ b/Documentation/filesystems/proc.rst
@@ -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

diff --git a/fs/proc/fd.c b/fs/proc/fd.c
index 6a80b40fd2fec84d417dd05212e0c6c1dbb26da3..172c86270b3127571e745528544583ae55ff449c 100644 (file)
--- a/fs/proc/fd.c
+++ b/fs/proc/fd.c
@@ -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);