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Subject[PATCH 23/25] fsinfo: debugfs - add sb operation fsinfo() [ver #14]
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From: Ian Kent <raven@themaw.net>

The new fsinfo() system call adds a new super block operation
->fsinfo() which is used by file systems to provide file
system specific information for fsinfo() requests.

The fsinfo() request FSINFO_ATTR_PARAMETERS provides the same
function as sb operation ->show_options() so it needs to be
implemented by any file system that provides ->show_options()
as a minimum.

Also add a simple FSINFO_ATTR_CAPABILITIES implementation.

Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: David Howells <dhowells@redhat.com>
---

fs/debugfs/inode.c | 38 ++++++++++++++++++++++++++++++++++++++
1 file changed, 38 insertions(+)

diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index 24354ccdc968..a5ef136addbb 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -24,6 +24,7 @@
#include <linux/seq_file.h>
#include <linux/magic.h>
#include <linux/slab.h>
+#include <linux/fsinfo.h>

#include "internal.h"

@@ -143,6 +144,40 @@ static int debugfs_show_options(struct seq_file *m, struct dentry *root)
return 0;
}

+#ifdef CONFIG_FSINFO
+/*
+ * Get filesystem information.
+ */
+static int debugfs_fsinfo(struct path *path, struct fsinfo_kparams *params)
+{
+ struct debugfs_fs_info *fsi = path->dentry->d_sb->s_fs_info;
+ struct fsinfo_capabilities *caps;
+
+ switch (params->request) {
+ case FSINFO_ATTR_CAPABILITIES:
+ caps = params->buffer;
+ fsinfo_set_cap(caps, FSINFO_CAP_IS_KERNEL_FS);
+ fsinfo_set_cap(caps, FSINFO_CAP_NOT_PERSISTENT);
+ return sizeof(*caps);
+
+ case FSINFO_ATTR_PARAMETERS:
+ fsinfo_note_sb_params(params, path->dentry->d_sb->s_flags);
+ if (!uid_eq(fsi->uid, GLOBAL_ROOT_UID))
+ fsinfo_note_paramf(params, "uid", "%u",
+ from_kuid_munged(&init_user_ns, fsi->uid));
+ if (!gid_eq(fsi->gid, GLOBAL_ROOT_GID))
+ fsinfo_note_paramf(params, "gid", "%u",
+ from_kgid_munged(&init_user_ns, fsi->gid));
+ if (fsi->mode != DEBUGFS_DEFAULT_MODE)
+ fsinfo_note_paramf(params, "mode", "%o", fsi->mode);
+ return params->usage;
+
+ default:
+ return generic_fsinfo(path, params);
+ }
+}
+#endif /* CONFIG_FSINFO */
+
static void debugfs_free_inode(struct inode *inode)
{
if (S_ISLNK(inode->i_mode))
@@ -154,6 +189,9 @@ static const struct super_operations debugfs_super_operations = {
.statfs = simple_statfs,
.show_options = debugfs_show_options,
.free_inode = debugfs_free_inode,
+#ifdef CONFIG_FSINFO
+ .fsinfo = debugfs_fsinfo,
+#endif
};

static void debugfs_release_dentry(struct dentry *dentry)
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