From fb2088ccc139ffbf1cf359216883712dab4ae43d Mon Sep 17 00:00:00 2001 From: Sachin Prabhu Date: Mon, 1 Aug 2011 12:10:12 +0100 Subject: nfs: Do not allow multiple mounts on same mountpoint when using -o noac Do not allow multiple mounts on same mountpoint when using -o noac When you normally attempt to mount a share twice on the same mountpoint, a check in do_add_mount causes it to return an error # mount localhost:/nfsv3 /mnt # mount localhost:/nfsv3 /mnt mount.nfs: /mnt is already mounted or busy However when using the option 'noac', the user is able to mount the same share on the same mountpoint multiple times. This happens because a share mounted with the noac option is automatically assigned the 'sync' flag MS_SYNCHRONOUS in nfs_initialise_sb(). This flag is set after the check for already existing superblocks is done in sget(). The check for the mount flags in nfs_compare_mount_options() does not take into account the 'sync' flag applied later on in the code path. This means that when using 'noac', a new superblock structure is assigned for every new mount of the same share and multiple shares on the same mountpoint are allowed. ie. # mount -onoac localhost:/nfsv3 /mnt can be run multiple times. The patch checks for noac and assigns the sync flag before sget() is called to obtain an already existing superblock structure. Signed-off-by: Sachin Prabhu Reviewed-by: Jeff Layton Signed-off-by: Trond Myklebust --- fs/nfs/super.c | 23 ++++++++++++++++++++--- 1 file changed, 20 insertions(+), 3 deletions(-) (limited to 'fs/nfs/super.c') diff --git a/fs/nfs/super.c b/fs/nfs/super.c index b961ceac66b4..9b7dd7013b15 100644 --- a/fs/nfs/super.c +++ b/fs/nfs/super.c @@ -2035,9 +2035,6 @@ static inline void nfs_initialise_sb(struct super_block *sb) sb->s_blocksize = nfs_block_bits(server->wsize, &sb->s_blocksize_bits); - if (server->flags & NFS_MOUNT_NOAC) - sb->s_flags |= MS_SYNCHRONOUS; - sb->s_bdi = &server->backing_dev_info; nfs_super_set_maxbytes(sb, server->maxfilesize); @@ -2249,6 +2246,10 @@ static struct dentry *nfs_fs_mount(struct file_system_type *fs_type, if (server->flags & NFS_MOUNT_UNSHARED) compare_super = NULL; + /* -o noac implies -o sync */ + if (server->flags & NFS_MOUNT_NOAC) + sb_mntdata.mntflags |= MS_SYNCHRONOUS; + /* Get a superblock - note that we may end up sharing one that already exists */ s = sget(fs_type, compare_super, nfs_set_super, &sb_mntdata); if (IS_ERR(s)) { @@ -2361,6 +2362,10 @@ nfs_xdev_mount(struct file_system_type *fs_type, int flags, if (server->flags & NFS_MOUNT_UNSHARED) compare_super = NULL; + /* -o noac implies -o sync */ + if (server->flags & NFS_MOUNT_NOAC) + sb_mntdata.mntflags |= MS_SYNCHRONOUS; + /* Get a superblock - note that we may end up sharing one that already exists */ s = sget(&nfs_fs_type, compare_super, nfs_set_super, &sb_mntdata); if (IS_ERR(s)) { @@ -2628,6 +2633,10 @@ nfs4_remote_mount(struct file_system_type *fs_type, int flags, if (server->flags & NFS4_MOUNT_UNSHARED) compare_super = NULL; + /* -o noac implies -o sync */ + if (server->flags & NFS_MOUNT_NOAC) + sb_mntdata.mntflags |= MS_SYNCHRONOUS; + /* Get a superblock - note that we may end up sharing one that already exists */ s = sget(&nfs4_fs_type, compare_super, nfs_set_super, &sb_mntdata); if (IS_ERR(s)) { @@ -2916,6 +2925,10 @@ nfs4_xdev_mount(struct file_system_type *fs_type, int flags, if (server->flags & NFS4_MOUNT_UNSHARED) compare_super = NULL; + /* -o noac implies -o sync */ + if (server->flags & NFS_MOUNT_NOAC) + sb_mntdata.mntflags |= MS_SYNCHRONOUS; + /* Get a superblock - note that we may end up sharing one that already exists */ s = sget(&nfs4_fs_type, compare_super, nfs_set_super, &sb_mntdata); if (IS_ERR(s)) { @@ -3003,6 +3016,10 @@ nfs4_remote_referral_mount(struct file_system_type *fs_type, int flags, if (server->flags & NFS4_MOUNT_UNSHARED) compare_super = NULL; + /* -o noac implies -o sync */ + if (server->flags & NFS_MOUNT_NOAC) + sb_mntdata.mntflags |= MS_SYNCHRONOUS; + /* Get a superblock - note that we may end up sharing one that already exists */ s = sget(&nfs4_fs_type, compare_super, nfs_set_super, &sb_mntdata); if (IS_ERR(s)) { -- cgit v1.2.3 From 815d405ceff0d6964683f033e18b9b23a88fba87 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Mon, 26 Sep 2011 20:36:09 -0400 Subject: VFS: Fix the remaining automounter semantics regressions The concensus seems to be that system calls such as stat() etc should not trigger an automount. Neither should the l* versions. This patch therefore adds a LOOKUP_AUTOMOUNT flag to tag those lookups that _should_ trigger an automount on the last path element. Signed-off-by: Trond Myklebust [ Edited to leave out the cases that are already covered by LOOKUP_OPEN, LOOKUP_DIRECTORY and LOOKUP_CREATE - all of which also fundamentally force automounting for their own reasons - Linus ] Signed-off-by: Linus Torvalds --- fs/namespace.c | 2 +- fs/nfs/super.c | 2 +- fs/quota/quota.c | 2 +- 3 files changed, 3 insertions(+), 3 deletions(-) (limited to 'fs/nfs/super.c') diff --git a/fs/namespace.c b/fs/namespace.c index 22bfe8273c68..b4febb29d3bb 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1757,7 +1757,7 @@ static int do_loopback(struct path *path, char *old_name, return err; if (!old_name || !*old_name) return -EINVAL; - err = kern_path(old_name, LOOKUP_FOLLOW, &old_path); + err = kern_path(old_name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &old_path); if (err) return err; diff --git a/fs/nfs/super.c b/fs/nfs/super.c index 9b7dd7013b15..5b19b6aabe18 100644 --- a/fs/nfs/super.c +++ b/fs/nfs/super.c @@ -2798,7 +2798,7 @@ static struct dentry *nfs_follow_remote_path(struct vfsmount *root_mnt, goto out_put_mnt_ns; ret = vfs_path_lookup(root_mnt->mnt_root, root_mnt, - export_path, LOOKUP_FOLLOW, &path); + export_path, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path); nfs_referral_loop_unprotect(); put_mnt_ns(ns_private); diff --git a/fs/quota/quota.c b/fs/quota/quota.c index b34bdb25490c..10b6be3ca280 100644 --- a/fs/quota/quota.c +++ b/fs/quota/quota.c @@ -355,7 +355,7 @@ SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special, * resolution (think about autofs) and thus deadlocks could arise. */ if (cmds == Q_QUOTAON) { - ret = user_path_at(AT_FDCWD, addr, LOOKUP_FOLLOW, &path); + ret = user_path_at(AT_FDCWD, addr, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path); if (ret) pathp = ERR_PTR(ret); else -- cgit v1.2.3 From 45402c38eec740f52422aafc92937c6a4a8c8c0e Mon Sep 17 00:00:00 2001 From: H Hartley Sweeten Date: Fri, 2 Sep 2011 14:39:12 -0700 Subject: nfs/super.c: local functions should be static commit ae50c0b5 "pnfs: client stats" added additional information to the output of /proc/self/mountstats. The new functions introduced are only used in this file and should be marked static. If CONFIG_NFS_V4_1 is not defined, empty stub functions are used. If CONFIG_NFS_V4 is not defined these stub functions are not used at all. Adding static for the functions results in compile warnings: fs/nfs/super.c:743: warning: 'show_sessions' defined but not used fs/nfs/super.c:756: warning: 'show_pnfs' defined but not used Fix this by adding a #ifdef CONFIG_NFS_V4 guard around the two show_ functions. Signed-off-by: H Hartley Sweeten Cc: Trond Myklebust Signed-off-by: Trond Myklebust --- fs/nfs/super.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) (limited to 'fs/nfs/super.c') diff --git a/fs/nfs/super.c b/fs/nfs/super.c index 5b19b6aabe18..480b3b6bf71e 100644 --- a/fs/nfs/super.c +++ b/fs/nfs/super.c @@ -733,18 +733,22 @@ static int nfs_show_options(struct seq_file *m, struct vfsmount *mnt) return 0; } + +#ifdef CONFIG_NFS_V4 #ifdef CONFIG_NFS_V4_1 -void show_sessions(struct seq_file *m, struct nfs_server *server) +static void show_sessions(struct seq_file *m, struct nfs_server *server) { if (nfs4_has_session(server->nfs_client)) seq_printf(m, ",sessions"); } #else -void show_sessions(struct seq_file *m, struct nfs_server *server) {} +static void show_sessions(struct seq_file *m, struct nfs_server *server) {} +#endif #endif +#ifdef CONFIG_NFS_V4 #ifdef CONFIG_NFS_V4_1 -void show_pnfs(struct seq_file *m, struct nfs_server *server) +static void show_pnfs(struct seq_file *m, struct nfs_server *server) { seq_printf(m, ",pnfs="); if (server->pnfs_curr_ld) @@ -752,9 +756,10 @@ void show_pnfs(struct seq_file *m, struct nfs_server *server) else seq_printf(m, "not configured"); } -#else /* CONFIG_NFS_V4_1 */ -void show_pnfs(struct seq_file *m, struct nfs_server *server) {} -#endif /* CONFIG_NFS_V4_1 */ +#else +static void show_pnfs(struct seq_file *m, struct nfs_server *server) {} +#endif +#endif static int nfs_show_devname(struct seq_file *m, struct vfsmount *mnt) { -- cgit v1.2.3