[PATCH 1/2] quota: Add mountpath based quota support
From: Sascha Hauer <s.hauer@pengutronix.de>
Date: 2021-02-11 15:34:26
Also in:
lkml
Subsystem:
diskquota, filesystems (vfs and infrastructure), the rest · Maintainers:
Jan Kara, Alexander Viro, Christian Brauner, Linus Torvalds
Add syscall quotactl_path, a variant of quotactl which allows to specify the mountpath instead of a path of to a block device. The quotactl syscall expects a path to the mounted block device to specify the filesystem to work on. This limits usage to filesystems which actually have a block device. quotactl_path replaces the path to the block device with a path where the filesystem is mounted at. The global Q_SYNC command to sync all filesystems is not supported for this new syscall, otherwise quotactl_path behaves like quotactl. Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de> --- fs/quota/quota.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+)
diff --git a/fs/quota/quota.c b/fs/quota/quota.c
index 6d16b2be5ac4..6f1df32abeea 100644
--- a/fs/quota/quota.c
+++ b/fs/quota/quota.c@@ -17,6 +17,7 @@ #include <linux/capability.h> #include <linux/quotaops.h> #include <linux/types.h> +#include <linux/mount.h> #include <linux/writeback.h> #include <linux/nospec.h> #include "compat.h"
@@ -968,3 +969,51 @@ SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special, path_put(pathp); return ret; } + +SYSCALL_DEFINE4(quotactl_path, unsigned int, cmd, const char __user *, + mountpoint, qid_t, id, void __user *, addr) +{ + struct super_block *sb; + struct path mountpath; + unsigned int cmds = cmd >> SUBCMDSHIFT; + unsigned int type = cmd & SUBCMDMASK; + int ret; + + if (type >= MAXQUOTAS) + return -EINVAL; + + if (!mountpoint) + return -ENODEV; + + ret = user_path_at(AT_FDCWD, mountpoint, + LOOKUP_FOLLOW | LOOKUP_AUTOMOUNT, &mountpath); + if (ret) + return ret; + + sb = mountpath.dentry->d_inode->i_sb; + + if (quotactl_cmd_write(cmds)) { + ret = mnt_want_write(mountpath.mnt); + if (ret) + goto out; + } + + if (quotactl_cmd_onoff(cmds)) + down_write(&sb->s_umount); + else + down_read(&sb->s_umount); + + ret = do_quotactl(sb, type, cmds, id, addr, ERR_PTR(-EINVAL)); + + if (quotactl_cmd_onoff(cmds)) + up_write(&sb->s_umount); + else + up_read(&sb->s_umount); + + if (quotactl_cmd_write(cmds)) + mnt_drop_write(mountpath.mnt); +out: + path_put(&mountpath); + + return ret; +}
--
2.20.1