From 9dfa23c8de925041b7b45637a1a80a98a22f19dd Mon Sep 17 00:00:00 2001 From: Sascha Hauer Date: Thu, 4 Mar 2021 13:35:39 +0100 Subject: quota: Add mountpath based quota support 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. Link: https://lore.kernel.org/r/20210304123541.30749-2-s.hauer@pengutronix.de Signed-off-by: Sascha Hauer Reviewed-by: Christoph Hellwig Signed-off-by: Jan Kara --- fs/quota/quota.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 46 insertions(+), 3 deletions(-) diff --git a/fs/quota/quota.c b/fs/quota/quota.c index 6d16b2be5ac4..f7b4b66491fc 100644 --- a/fs/quota/quota.c +++ b/fs/quota/quota.c @@ -17,6 +17,7 @@ #include #include #include +#include #include #include #include "compat.h" @@ -827,8 +828,6 @@ static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id, } } -#ifdef CONFIG_BLOCK - /* Return 1 if 'cmd' will block on frozen filesystem */ static int quotactl_cmd_write(int cmd) { @@ -850,7 +849,6 @@ static int quotactl_cmd_write(int cmd) } return 1; } -#endif /* CONFIG_BLOCK */ /* Return true if quotactl command is manipulating quota on/off state */ static bool quotactl_cmd_onoff(int cmd) @@ -968,3 +966,48 @@ out: 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; + + ret = user_path_at(AT_FDCWD, mountpoint, + LOOKUP_FOLLOW | LOOKUP_AUTOMOUNT, &mountpath); + if (ret) + return ret; + + sb = mountpath.mnt->mnt_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; +} -- cgit v1.2.3