From: David Howells <dhowells@redhat.com>
To: viro@zeniv.linux.org.uk
Cc: dhowells@redhat.com, raven@themaw.net, mszeredi@redhat.com,
linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [PATCH 03/25] vfs: Allow fsinfo() to query what's in an fs_context [ver #14]
Date: Mon, 24 Jun 2019 15:09:14 +0100 [thread overview]
Message-ID: <156138535407.25627.15015993364565647650.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <156138532485.25627.7459410522109581052.stgit@warthog.procyon.org.uk>
Allow fsinfo() to be used to query the filesystem attached to an fs_context
once a superblock has been created or if it comes from fspick().
The caller must specify AT_FSINFO_FROM_FSOPEN in the parameters and must
supply the fd from fsopen() as dfd and must set filename to NULL.
This is done with something like:
fd = fsopen("ext4", 0);
...
struct fsinfo_params params = {
.at_flags = AT_FSINFO_FROM_FSOPEN;
...
};
fsinfo(fd, NULL, ¶ms, ...);
Signed-off-by: David Howells <dhowells@redhat.com>
---
fs/fsinfo.c | 46 +++++++++++++++++++++++++++++++++++++++++++-
fs/statfs.c | 2 +-
include/uapi/linux/fcntl.h | 2 ++
3 files changed, 48 insertions(+), 2 deletions(-)
diff --git a/fs/fsinfo.c b/fs/fsinfo.c
index 49b46f96dda3..c24701f994d1 100644
--- a/fs/fsinfo.c
+++ b/fs/fsinfo.c
@@ -8,6 +8,7 @@
#include <linux/security.h>
#include <linux/uaccess.h>
#include <linux/fsinfo.h>
+#include <linux/fs_context.h>
#include <uapi/linux/mount.h>
#include "internal.h"
@@ -340,6 +341,42 @@ static int vfs_fsinfo_fd(unsigned int fd, struct fsinfo_kparams *params)
return ret;
}
+/*
+ * Allow access to an fs_context object as created by fsopen() or fspick().
+ */
+static int vfs_fsinfo_fscontext(int fd, struct fsinfo_kparams *params)
+{
+ struct fs_context *fc;
+ struct fd f = fdget(fd);
+ int ret;
+
+ if (!f.file)
+ return -EBADF;
+
+ ret = -EINVAL;
+ if (f.file->f_op == &fscontext_fops)
+ goto out_f;
+ ret = -EOPNOTSUPP;
+ if (fc->ops == &legacy_fs_context_ops)
+ goto out_f;
+
+ ret = mutex_lock_interruptible(&fc->uapi_mutex);
+ if (ret == 0) {
+ ret = -EIO;
+ if (fc->root) {
+ struct path path = { .dentry = fc->root };
+
+ ret = vfs_fsinfo(&path, params);
+ }
+
+ mutex_unlock(&fc->uapi_mutex);
+ }
+
+out_f:
+ fdput(f);
+ return ret;
+}
+
/*
* Return buffer information by requestable attribute.
*
@@ -445,6 +482,9 @@ SYSCALL_DEFINE5(fsinfo,
params.request = user_params.request;
params.Nth = user_params.Nth;
params.Mth = user_params.Mth;
+
+ if ((params.at_flags & AT_FSINFO_FROM_FSOPEN) && filename)
+ return -EINVAL;
} else {
params.request = FSINFO_ATTR_STATFS;
}
@@ -453,6 +493,8 @@ SYSCALL_DEFINE5(fsinfo,
user_buf_size = 0;
user_buffer = NULL;
}
+ if ((params.at_flags & AT_FSINFO_FROM_FSOPEN) && filename)
+ return -EINVAL;
/* Allocate an appropriately-sized buffer. We will truncate the
* contents when we write the contents back to userspace.
@@ -500,7 +542,9 @@ SYSCALL_DEFINE5(fsinfo,
if (!params.buffer)
goto error_scratch;
- if (filename)
+ if (params.at_flags & AT_FSINFO_FROM_FSOPEN)
+ ret = vfs_fsinfo_fscontext(dfd, ¶ms);
+ else if (filename)
ret = vfs_fsinfo_path(dfd, filename, ¶ms);
else
ret = vfs_fsinfo_fd(dfd, ¶ms);
diff --git a/fs/statfs.c b/fs/statfs.c
index eea7af6f2f22..b9b63d9f4f24 100644
--- a/fs/statfs.c
+++ b/fs/statfs.c
@@ -86,7 +86,7 @@ int vfs_statfs(const struct path *path, struct kstatfs *buf)
int error;
error = statfs_by_dentry(path->dentry, buf);
- if (!error)
+ if (!error && path->mnt)
buf->f_flags = calculate_f_flags(path->mnt);
return error;
}
diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h
index 1d338357df8a..6a2402a8fa30 100644
--- a/include/uapi/linux/fcntl.h
+++ b/include/uapi/linux/fcntl.h
@@ -91,6 +91,8 @@
#define AT_STATX_FORCE_SYNC 0x2000 /* - Force the attributes to be sync'd with the server */
#define AT_STATX_DONT_SYNC 0x4000 /* - Don't sync attributes with the server */
+#define AT_FSINFO_FROM_FSOPEN 0x2000 /* Examine the fs_context attached to dfd by fsopen() */
+
#define AT_RECURSIVE 0x8000 /* Apply to the entire subtree */
next prev parent reply other threads:[~2019-06-24 14:09 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-24 14:08 [PATCH 00/25] VFS: Introduce filesystem information query syscall [ver #14] David Howells
2019-06-24 14:08 ` [PATCH 01/25] vfs: syscall: Add fsinfo() to query filesystem information " David Howells
2019-06-25 8:28 ` Christian Brauner
2019-06-26 9:49 ` David Howells
2019-06-26 9:58 ` Christian Brauner
2019-06-24 14:09 ` [PATCH 02/25] fsinfo: Add syscalls to other arches " David Howells
2019-06-25 9:31 ` Christian Brauner
2019-06-24 14:09 ` David Howells [this message]
2019-06-25 9:27 ` [PATCH 03/25] vfs: Allow fsinfo() to query what's in an fs_context " Christian Brauner
2019-06-26 10:02 ` David Howells
2019-06-26 10:06 ` Christian Brauner
2019-06-24 14:09 ` [PATCH 04/25] vfs: Allow fsinfo() to be used to query an fs parameter description " David Howells
2019-06-25 9:40 ` Christian Brauner
2019-06-24 14:09 ` [PATCH 05/25] vfs: Implement parameter value retrieval with fsinfo() " David Howells
2019-06-25 9:44 ` Christian Brauner
2019-06-24 14:09 ` [PATCH 06/25] fsinfo: Implement retrieval of LSM parameters " David Howells
2019-06-24 14:09 ` [PATCH 07/25] vfs: Introduce a non-repeating system-unique superblock ID " David Howells
2019-06-24 14:09 ` [PATCH 08/25] vfs: Allow fsinfo() to look up a mount object by " David Howells
2019-06-26 9:49 ` Christian Brauner
2019-06-24 14:10 ` [PATCH 09/25] vfs: Add mount notification count " David Howells
2019-06-26 9:52 ` Christian Brauner
2019-06-24 14:10 ` [PATCH 10/25] vfs: Allow mount information to be queried by fsinfo() " David Howells
2019-06-26 9:53 ` Christian Brauner
2019-06-24 14:10 ` [PATCH 11/25] vfs: fsinfo sample: Mount listing program " David Howells
2019-06-24 14:10 ` [PATCH 12/25] fsinfo: Add API documentation " David Howells
2019-06-24 14:10 ` [PATCH 13/25] hugetlbfs: Add support for fsinfo() " David Howells
2019-06-24 14:10 ` [PATCH 14/25] kernfs, cgroup: Add fsinfo support " David Howells
2019-06-24 14:11 ` [PATCH 15/25] fsinfo: Support SELinux superblock parameter retrieval " David Howells
2019-06-24 14:11 ` [PATCH 16/25] fsinfo: Support Smack " David Howells
2019-06-24 14:11 ` [PATCH 17/25] afs: Support fsinfo() " David Howells
2019-06-24 14:11 ` [PATCH 18/25] fsinfo: proc - add sb operation " David Howells
2019-06-24 14:11 ` [PATCH 19/25] fsinfo: autofs " David Howells
2019-06-24 14:11 ` [PATCH 20/25] fsinfo: shmem - add tmpfs " David Howells
2019-06-24 14:11 ` [PATCH 21/25] fsinfo: devpts - add " David Howells
2019-06-24 14:12 ` [PATCH 22/25] fsinfo: pstore " David Howells
2019-06-24 14:12 ` [PATCH 23/25] fsinfo: debugfs " David Howells
2019-06-24 14:12 ` [PATCH 24/25] fsinfo: bpf " David Howells
2019-06-24 14:12 ` [PATCH 25/25] fsinfo: ufs " David Howells
2019-06-26 10:05 ` [PATCH 00/25] VFS: Introduce filesystem information query syscall " Christian Brauner
2019-06-26 10:42 ` Ian Kent
2019-06-26 10:47 ` Christian Brauner
2019-06-27 0:38 ` Ian Kent
2019-06-26 13:19 ` Christian Brauner
2019-06-26 14:31 ` David Howells
2019-06-26 14:50 ` Christian Brauner
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