This patch extends /proc/<pid>/fdinfo/<fd> to report information about open
files, and pathname. This information can be useful to know when debugging an
application.
For each file descriptor, the information is provided in the following format:
kerndev: ~/code/kernel# cat /proc/`pgrep pickup`/fdinfo/6
mode: 0622
dev: 253,0
ino: 21463057
uid: 89
gid: 89
rdev: 0,0
pos: 0
flags: 04002 FD_CLOEXEC # if close-on-exec flag is set
path: /var/spool/postfix/public/pickup
You can also use this to find out more information about locked open files:
kerndev: /proc# cat /proc/locks
1: POSIX ADVISORY WRITE 2663 fd:00:21398205 0 EOF
^^^^ ^^^^^^^^
2: FLOCK ADVISORY WRITE 2654 fd:00:21398203 0 EOF
3: FLOCK ADVISORY WRITE 2564 fd:00:21463056 0 EOF
4: FLOCK ADVISORY WRITE 2266 fd:00:21398151 0 EOF
kerndev: /proc# cd 2663/fdinfo/
kerndev: /proc/2663/fdinfo# grep 21398205 * -B2 -A6
^^^^
3-mode: 0644
3-dev: 253,0
3:ino: 21398205
^^^^^^^^
3-uid: 0
3-gid: 0
3-rdev: 0,0
3-pos: 5
3-flags: 02 FD_CLOEXEC
3-path: /var/run/atd.pid
Signed-off-by: Eugene Teo <[email protected]>
---
fs/proc/base.c | 47 +++++++++++++++++++++++++++++++++++++++++------
1 files changed, 41 insertions(+), 6 deletions(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index c59852b..dde617f 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1402,7 +1402,7 @@ out:
return ~0U;
}
-#define PROC_FDINFO_MAX 64
+#define PROC_FDINFO_MAX 256
static int proc_fd_info(struct inode *inode, struct dentry **dentry,
struct vfsmount **mnt, char *info)
@@ -1411,6 +1411,7 @@ static int proc_fd_info(struct inode *inode, struct dentry **dentry,
struct files_struct *files = NULL;
struct file *file;
int fd = proc_fd(inode);
+ int ret = -ENOENT;
if (task) {
files = get_files_struct(task);
@@ -1424,24 +1425,58 @@ static int proc_fd_info(struct inode *inode, struct dentry **dentry,
spin_lock(&files->file_lock);
file = fcheck_files(files, fd);
if (file) {
+ ret = 0;
+
if (mnt)
*mnt = mntget(file->f_path.mnt);
if (dentry)
*dentry = dget(file->f_path.dentry);
- if (info)
+ /* called by proc_fdinfo_read() */
+ if (info) {
+ struct fdtable *fdt = files_fdtable(files);
+ struct dentry *d = dget(file->f_path.dentry);
+ struct vfsmount *v = mntget(file->f_path.mnt);
+ char *page = (char *)__get_free_page(GFP_TEMPORARY);
+ int gcoe = FD_ISSET(fd, fdt->close_on_exec);
+ int dev_nr = d->d_inode->i_sb->s_dev;
+ int rdev_nr = d->d_inode->i_rdev;
+
+ if (!page) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
snprintf(info, PROC_FDINFO_MAX,
+ "mode:\t0%o\n"
+ "dev:\t%d,%d\n"
+ "ino:\t%ld\n"
+ "uid:\t%d\n"
+ "gid:\t%d\n"
+ "rdev:\t%d,%d\n"
"pos:\t%lli\n"
- "flags:\t0%o\n",
+ "flags:\t0%o %s\n"
+ "path:\t%s\n",
+ d->d_inode->i_mode & 0777,
+ MAJOR(dev_nr), MINOR(dev_nr),
+ d->d_inode->i_ino,
+ file->f_uid, file->f_gid,
+ MAJOR(rdev_nr), MINOR(rdev_nr),
(long long) file->f_pos,
- file->f_flags);
+ file->f_flags, gcoe ? "FD_CLOEXEC" : "",
+ d_path(d, v, page, PAGE_SIZE));
+ free_page((unsigned long)page);
+out:
+ mntput(v);
+ dput(d);
+ }
spin_unlock(&files->file_lock);
put_files_struct(files);
- return 0;
+ return ret;
}
spin_unlock(&files->file_lock);
put_files_struct(files);
}
- return -ENOENT;
+ return ret;
}
static int proc_fd_link(struct inode *inode, struct dentry **dentry,
On Sat, 2008-02-09 at 20:01 +0800, Eugene Teo wrote:
> This patch extends /proc/<pid>/fdinfo/<fd> to report information about open
> files, and pathname. This information can be useful to know when debugging an
> application.
>
> For each file descriptor, the information is provided in the following format:
>
> kerndev: ~/code/kernel# cat /proc/`pgrep pickup`/fdinfo/6
> mode: 0622
> dev: 253,0
> ino: 21463057
These are already available via 'stat /proc/<pid>/fd/<fd>'
> uid: 89
> gid: 89
AFAICS file->f_[ug]id are only used by the netfilter code, but I guess
it wouldn't hurt to show them here. But please add fields at the end of
the file, instead of the beggining.
> rdev: 0,0
This is in struct stat too.
> pos: 0
> flags: 04002 FD_CLOEXEC # if close-on-exec flag is set
FD_CLOEXEC should be on a separate line, because it's not an O_FOO flag.
> path: /var/spool/postfix/public/pickup
readlink /proc/<pid>/fd/<fd>
Thanks,
Miklos
>
> You can also use this to find out more information about locked open files:
>
> kerndev: /proc# cat /proc/locks
> 1: POSIX ADVISORY WRITE 2663 fd:00:21398205 0 EOF
> ^^^^ ^^^^^^^^
> 2: FLOCK ADVISORY WRITE 2654 fd:00:21398203 0 EOF
> 3: FLOCK ADVISORY WRITE 2564 fd:00:21463056 0 EOF
> 4: FLOCK ADVISORY WRITE 2266 fd:00:21398151 0 EOF
> kerndev: /proc# cd 2663/fdinfo/
> kerndev: /proc/2663/fdinfo# grep 21398205 * -B2 -A6
> ^^^^
> 3-mode: 0644
> 3-dev: 253,0
> 3:ino: 21398205
> ^^^^^^^^
> 3-uid: 0
> 3-gid: 0
> 3-rdev: 0,0
> 3-pos: 5
> 3-flags: 02 FD_CLOEXEC
> 3-path: /var/run/atd.pid
>
> Signed-off-by: Eugene Teo <[email protected]>
> ---
> fs/proc/base.c | 47 +++++++++++++++++++++++++++++++++++++++++------
> 1 files changed, 41 insertions(+), 6 deletions(-)
>
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index c59852b..dde617f 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -1402,7 +1402,7 @@ out:
> return ~0U;
> }
>
> -#define PROC_FDINFO_MAX 64
> +#define PROC_FDINFO_MAX 256
>
> static int proc_fd_info(struct inode *inode, struct dentry **dentry,
> struct vfsmount **mnt, char *info)
> @@ -1411,6 +1411,7 @@ static int proc_fd_info(struct inode *inode, struct dentry **dentry,
> struct files_struct *files = NULL;
> struct file *file;
> int fd = proc_fd(inode);
> + int ret = -ENOENT;
>
> if (task) {
> files = get_files_struct(task);
> @@ -1424,24 +1425,58 @@ static int proc_fd_info(struct inode *inode, struct dentry **dentry,
> spin_lock(&files->file_lock);
> file = fcheck_files(files, fd);
> if (file) {
> + ret = 0;
> +
> if (mnt)
> *mnt = mntget(file->f_path.mnt);
> if (dentry)
> *dentry = dget(file->f_path.dentry);
> - if (info)
> + /* called by proc_fdinfo_read() */
> + if (info) {
> + struct fdtable *fdt = files_fdtable(files);
> + struct dentry *d = dget(file->f_path.dentry);
> + struct vfsmount *v = mntget(file->f_path.mnt);
> + char *page = (char *)__get_free_page(GFP_TEMPORARY);
> + int gcoe = FD_ISSET(fd, fdt->close_on_exec);
> + int dev_nr = d->d_inode->i_sb->s_dev;
> + int rdev_nr = d->d_inode->i_rdev;
> +
> + if (!page) {
> + ret = -ENOMEM;
> + goto out;
> + }
> +
> snprintf(info, PROC_FDINFO_MAX,
> + "mode:\t0%o\n"
> + "dev:\t%d,%d\n"
> + "ino:\t%ld\n"
> + "uid:\t%d\n"
> + "gid:\t%d\n"
> + "rdev:\t%d,%d\n"
> "pos:\t%lli\n"
> - "flags:\t0%o\n",
> + "flags:\t0%o %s\n"
> + "path:\t%s\n",
> + d->d_inode->i_mode & 0777,
> + MAJOR(dev_nr), MINOR(dev_nr),
> + d->d_inode->i_ino,
> + file->f_uid, file->f_gid,
> + MAJOR(rdev_nr), MINOR(rdev_nr),
> (long long) file->f_pos,
> - file->f_flags);
> + file->f_flags, gcoe ? "FD_CLOEXEC" : "",
> + d_path(d, v, page, PAGE_SIZE));
> + free_page((unsigned long)page);
> +out:
> + mntput(v);
> + dput(d);
> + }
> spin_unlock(&files->file_lock);
> put_files_struct(files);
> - return 0;
> + return ret;
> }
> spin_unlock(&files->file_lock);
> put_files_struct(files);
> }
> - return -ENOENT;
> + return ret;
> }
>
> static int proc_fd_link(struct inode *inode, struct dentry **dentry,
>
Hi Eugene
In general, I think this patch isn't wrong idea.
but it shuld be brush up more, may be.
> kerndev: ~/code/kernel# cat /proc/`pgrep pickup`/fdinfo/6
> mode: 0622
I think this is inode attribute, but not fd attribute.
> dev: 253,0
> ino: 21463057
may be useful, agreed with you :)
> uid: 89
> gid: 89
> rdev: 0,0
> pos: 0
> flags: 04002 FD_CLOEXEC # if close-on-exec flag is set
agreed with Miklos's opinion.
> path: /var/spool/postfix/public/pickup
may be, we shold think namespace..
> You can also use this to find out more information about locked open files:
is your requirement only fd -> ino pick up?
Hi Miklos,
<quote sender="Miklos Szeredi">
> On Sat, 2008-02-09 at 20:01 +0800, Eugene Teo wrote:
> > This patch extends /proc/<pid>/fdinfo/<fd> to report information about open
> > files, and pathname. This information can be useful to know when debugging an
> > application.
> >
> > For each file descriptor, the information is provided in the following format:
> >
> > kerndev: ~/code/kernel# cat /proc/`pgrep pickup`/fdinfo/6
> > mode: 0622
> > dev: 253,0
> > ino: 21463057
>
> These are already available via 'stat /proc/<pid>/fd/<fd>'
>
> > uid: 89
> > gid: 89
>
> AFAICS file->f_[ug]id are only used by the netfilter code, but I guess
> it wouldn't hurt to show them here. But please add fields at the end of
> the file, instead of the beggining.
Ok, will do.
> > rdev: 0,0
>
> This is in struct stat too.
>
> > pos: 0
> > flags: 04002 FD_CLOEXEC # if close-on-exec flag is set
>
> FD_CLOEXEC should be on a separate line, because it's not an O_FOO flag.
> > path: /var/spool/postfix/public/pickup
>
> readlink /proc/<pid>/fd/<fd>
Thanks for the review. I agree that some of the information can be omitted
since it can be accessed using stat and readlink. I still think it is useful
to have ino in the output though.
Here's the updated patch:
[PATCH] proc: extend /proc/<pid>/fdinfo/<fd>
This patch extends /proc/<pid>/fdinfo/<fd> to report information about open
files, and pathname. This information can be useful to know when debugging an
application.
For each file descriptor, the information is provided in the following format:
kerndev: ~/code/kernel$ cat /proc/`pgrep firefox-bin`/fdinfo/29
pos: 49152
flags: 02
uid: 500
gid: 500
ino: 13205793
fd_flags: FD_CLOEXEC # if close-on-exec flag is set
Signed-off-by: Eugene Teo <[email protected]>
---
fs/proc/base.c | 22 ++++++++++++++++++----
1 file changed, 18 insertions(+), 4 deletions(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index c59852b..5ea5dee 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1402,7 +1402,7 @@ out:
return ~0U;
}
-#define PROC_FDINFO_MAX 64
+#define PROC_FDINFO_MAX 128
static int proc_fd_info(struct inode *inode, struct dentry **dentry,
struct vfsmount **mnt, char *info)
@@ -1428,12 +1428,26 @@ static int proc_fd_info(struct inode *inode, struct dentry **dentry,
*mnt = mntget(file->f_path.mnt);
if (dentry)
*dentry = dget(file->f_path.dentry);
- if (info)
+ /* called by proc_fdinfo_read() */
+ if (info) {
+ struct fdtable *fdt = files_fdtable(files);
+ struct dentry *d = dget(file->f_path.dentry);
+ int gcoe = FD_ISSET(fd, fdt->close_on_exec);
+
snprintf(info, PROC_FDINFO_MAX,
"pos:\t%lli\n"
- "flags:\t0%o\n",
+ "flags:\t0%o\n"
+ "uid:\t%d\n"
+ "gid:\t%d\n"
+ "ino:\t%ld\n"
+ "fd_flags:\t%s\n",
(long long) file->f_pos,
- file->f_flags);
+ file->f_flags,
+ file->f_uid, file->f_gid,
+ d->d_inode->i_ino,
+ gcoe ? "FD_CLOEXEC" : "0");
+ dput(d);
+ }
spin_unlock(&files->file_lock);
put_files_struct(files);
return 0;
Hi Motohiro-san,
<quote sender="KOSAKI Motohiro">
> In general, I think this patch isn't wrong idea.
> but it shuld be brush up more, may be.
Thanks.
> > kerndev: ~/code/kernel# cat /proc/`pgrep pickup`/fdinfo/6
> > mode: 0622
>
> I think this is inode attribute, but not fd attribute.
Yes, it is an inode attribute.
> > dev: 253,0
> > ino: 21463057
>
> may be useful, agreed with you :)
Thanks.
> > uid: 89
> > gid: 89
> > rdev: 0,0
> > pos: 0
> > flags: 04002 FD_CLOEXEC # if close-on-exec flag is set
>
> agreed with Miklos's opinion.
>
> > path: /var/spool/postfix/public/pickup
>
> may be, we shold think namespace..
Besides readlink, this info can be gathered by running:
ls -laF /proc/<pid>/fd/<fd>
So, I agree with Miklo's opinion that we can omit this in the output.
> > You can also use this to find out more information about locked open files:
>
> is your requirement only fd -> ino pick up?
Not only this, but it is useful to know quickly if the open file descriptor
has a close-on-exec flag set.
Thanks,
Eugene