[Linaro-mm-sig] Re: [RFC PATCH] procfs: Add file path and size to /proc/<pid>/fdinfo

On Thu, May 19, 2022 at 2:47 PM Randy Dunlap rdunlap@infradead.org wrote:

Hi--

On 5/19/22 14:40, Kalesh Singh wrote:

...

diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst index 061744c436d9..ad66d78aca51 100644 --- a/Documentation/filesystems/proc.rst +++ b/Documentation/filesystems/proc.rst @@ -1922,13 +1922,16 @@ 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 four fields -- 'pos', 'flags', 'mnt_id' and 'ino'. +files have at least six fields -- 'pos', 'flags', 'mnt_id', 'ino', 'size', +and 'path'.

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. +the file, 'size' represents the size of the file in bytes, and 'path' +represents the file path.

A typical output is::

@@ -1936,6 +1939,8 @@ A typical output is:: flags: 0100002 mnt_id: 19 ino: 63107

•    size:   0
  

•    path:   /dev/null
  
  

All locks associated with a file descriptor are shown in its fdinfo too::

@@ -1953,6 +1958,8 @@ Eventfd files flags: 04002 mnt_id: 9 ino: 63107

•    size:   0
  

•    path:   anon_inode:[eventfd]
  eventfd-count:  5a
  
  

where 'eventfd-count' is hex value of a counter. @@ -1966,6 +1973,8 @@ Signalfd files flags: 04002 mnt_id: 9 ino: 63107

•    size:   0
  

•    path:   anon_inode:[signalfd]
  sigmask:        0000000000000200
  
  

where 'sigmask' is hex value of the signal mask associated @@ -1980,6 +1989,8 @@ Epoll files flags: 02 mnt_id: 9 ino: 63107

•    size:   0
  

•    path:   anon_inode:[eventpoll]
  tfd:        5 events:       1d data: ffffffffffffffff pos:0 ino:61af sdev:7
  
  

where 'tfd' is a target file descriptor number in decimal form, @@ -1998,6 +2009,8 @@ For inotify files the format is the following:: flags: 02000000 mnt_id: 9 ino: 63107

•    size:   0
  

•    path:   anon_inode:inotify
  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 @@ -2021,6 +2034,8 @@ For fanotify files the format is:: flags: 02 mnt_id: 9 ino: 63107

•    size:   0
  

•    path:   anon_inode:[fanotify]
  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
  

@@ -2046,6 +2061,8 @@ Timerfd files flags: 02 mnt_id: 9 ino: 63107

•    size:   0
  

•    path:   anon_inode:[timerfd]
  clockid: 0
  ticks: 0
  settime flags: 01
  

@@ -2070,6 +2087,7 @@ DMA Buffer files mnt_id: 9 ino: 63107 size: 32768

•    path:   /dmabuf:
  count:  2
  exp_name:  system-heap
  

All of these added lines should be indented with a tab instead of spaces.

Ahh. Thanks for catching it. WIll update in the next version.

-Kalesh

thanks.

~Randy

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