This patch introduces the Q_PATH flag to the quotactl cmd argument.
When given, the path given in the special argument to quotactl will
be the mount path where the filesystem is mounted, instead of a path
to the block device.
This is necessary for filesystems which do not have a block device as
backing store. Particularly this is done for upcoming UBIFS support.
Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
---
fs/quota/quota.c | 37 ++++++++++++++++++++++++++++---------
include/uapi/linux/quota.h | 1 +
2 files changed, 29 insertions(+), 9 deletions(-)
diff --git a/fs/quota/quota.c b/fs/quota/quota.c
index cb13fb76dbee..035cdd1b022b 100644
--- a/fs/quota/quota.c
+++ b/fs/quota/quota.c
@@ -19,6 +19,7 @@
#include <linux/types.h>
#include <linux/writeback.h>
#include <linux/nospec.h>
+#include <linux/mount.h>
static int check_quotactl_permission(struct super_block *sb, int type, int cmd,
qid_t id)
@@ -825,12 +826,16 @@ int kernel_quotactl(unsigned int cmd, const char __user *special,
{
uint cmds, type;
struct super_block *sb = NULL;
- struct path path, *pathp = NULL;
+ struct path path, *pathp = NULL, qpath;
int ret;
+ bool q_path;
cmds = cmd >> SUBCMDSHIFT;
type = cmd & SUBCMDMASK;
+ q_path = cmds & Q_PATH;
+ cmds &= ~Q_PATH;
+
/*
* As a special case Q_SYNC can be called without a specific device.
* It will iterate all superblocks that have quota enabled and call
@@ -855,19 +860,33 @@ int kernel_quotactl(unsigned int cmd, const char __user *special,
pathp = &path;
}
- sb = quotactl_block(special, cmds);
- if (IS_ERR(sb)) {
- ret = PTR_ERR(sb);
- goto out;
+ if (q_path) {
+ ret = user_path_at(AT_FDCWD, special, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT,
+ &qpath);
+ if (ret)
+ goto out1;
+
+ sb = qpath.mnt->mnt_sb;
+ } else {
+ sb = quotactl_block(special, cmds);
+ if (IS_ERR(sb)) {
+ ret = PTR_ERR(sb);
+ goto out;
+ }
}
ret = do_quotactl(sb, type, cmds, id, addr, pathp);
- if (!quotactl_cmd_onoff(cmds))
- drop_super(sb);
- else
- drop_super_exclusive(sb);
+ if (!q_path) {
+ if (!quotactl_cmd_onoff(cmds))
+ drop_super(sb);
+ else
+ drop_super_exclusive(sb);
+ }
out:
+ if (q_path)
+ path_put(&qpath);
+out1:
if (pathp && !IS_ERR(pathp))
path_put(pathp);
return ret;
diff --git a/include/uapi/linux/quota.h b/include/uapi/linux/quota.h
index f17c9636a859..e1787c0df601 100644
--- a/include/uapi/linux/quota.h
+++ b/include/uapi/linux/quota.h
@@ -71,6 +71,7 @@
#define Q_GETQUOTA 0x800007 /* get user quota structure */
#define Q_SETQUOTA 0x800008 /* set user quota structure */
#define Q_GETNEXTQUOTA 0x800009 /* get disk limits and usage >= ID */
+#define Q_PATH 0x400000 /* quotactl special arg contains mount path */
/* Quota format type IDs */
#define QFMT_VFS_OLD 1
--
2.24.0.rc1
