From: Valerie Aurora <vaurora@redhat.com> To: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Miklos Szeredi <miklos@szeredi.hu>, Jan Blunck <jblunck@suse.de>, Christoph Hellwig <hch@infradead.org>, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Valerie Aurora <vaurora@redhat.com>, autofs@linux.kernel.org, Alexander Viro <viro@zeniv.linux.org.uk> Subject: [PATCH 04/38] autofs4: Save autofs trigger's vfsmount in super block info Date: Fri, 25 Jun 2010 12:04:54 -0700 [thread overview] Message-ID: <1277492728-11446-5-git-send-email-vaurora@redhat.com> (raw) In-Reply-To: <1277492728-11446-1-git-send-email-vaurora@redhat.com> From: Jan Blunck <jblunck@suse.de> XXX - This is broken and included just to make union mounts work. See discussion at: http://kerneltrap.org/mailarchive/linux-fsdevel/2010/1/15/6708053/thread Original commit message: This is a bugfix/replacement for commit 051d381259eb57d6074d02a6ba6e90e744f1a29f: During a path walk if an autofs trigger is mounted on a dentry, when the follow_link method is called, the nameidata struct contains the vfsmount and mountpoint dentry of the parent mount while the dentry that is passed in is the root of the autofs trigger mount. I believe it is impossible to get the vfsmount of the trigger mount, within the follow_link method, when only the parent vfsmount and the root dentry of the trigger mount are known. The solution in this commit was to replace the path embedded in the parent's nameidata with the path of the link itself in __do_follow_link(). This is a relatively harmless misuse of the field, but union mounts ran into a bug during follow_link() caused by the nameidata containing the wrong path (we count on it being what it is all other places - the path of the parent). A cleaner and easier to understand solution is to save the necessary vfsmount in the autofs superblock info when it is mounted. Then we can easily update the vfsmount in autofs4_follow_link(). Signed-off-by: Jan Blunck <jblunck@suse.de> Signed-off-by: Valerie Aurora <vaurora@redhat.com> Acked-by: Ian Kent <raven@themaw.net> Cc: autofs@linux.kernel.org Cc: Alexander Viro <viro@zeniv.linux.org.uk> --- fs/autofs4/autofs_i.h | 1 + fs/autofs4/init.c | 11 ++++++++++- fs/autofs4/root.c | 6 ++++++ fs/namei.c | 7 ++----- 4 files changed, 19 insertions(+), 6 deletions(-) diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h index 3d283ab..de3af64 100644 --- a/fs/autofs4/autofs_i.h +++ b/fs/autofs4/autofs_i.h @@ -133,6 +133,7 @@ struct autofs_sb_info { int reghost_enabled; int needs_reghost; struct super_block *sb; + struct vfsmount *mnt; struct mutex wq_mutex; spinlock_t fs_lock; struct autofs_wait_queue *queues; /* Wait queue pointer */ diff --git a/fs/autofs4/init.c b/fs/autofs4/init.c index 9722e4b..5e0dcd7 100644 --- a/fs/autofs4/init.c +++ b/fs/autofs4/init.c @@ -17,7 +17,16 @@ static int autofs_get_sb(struct file_system_type *fs_type, int flags, const char *dev_name, void *data, struct vfsmount *mnt) { - return get_sb_nodev(fs_type, flags, data, autofs4_fill_super, mnt); + struct autofs_sb_info *sbi; + int ret; + + ret = get_sb_nodev(fs_type, flags, data, autofs4_fill_super, mnt); + if (ret) + return ret; + + sbi = autofs4_sbi(mnt->mnt_sb); + sbi->mnt = mnt; + return 0; } static struct file_system_type autofs_fs_type = { diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c index e8e5e63..c41e01d 100644 --- a/fs/autofs4/root.c +++ b/fs/autofs4/root.c @@ -219,6 +219,12 @@ static void *autofs4_follow_link(struct dentry *dentry, struct nameidata *nd) DPRINTK("dentry=%p %.*s oz_mode=%d nd->flags=%d", dentry, dentry->d_name.len, dentry->d_name.name, oz_mode, nd->flags); + + dput(nd->path.dentry); + mntput(nd->path.mnt); + nd->path.mnt = mntget(sbi->mnt); + nd->path.dentry = dget(dentry); + /* * For an expire of a covered direct or offset mount we need * to break out of follow_down() at the autofs mount trigger diff --git a/fs/namei.c b/fs/namei.c index 3b43c48..f731108 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -538,11 +538,8 @@ __do_follow_link(struct path *path, struct nameidata *nd, void **p) touch_atime(path->mnt, dentry); nd_set_link(nd, NULL); - if (path->mnt != nd->path.mnt) { - path_to_nameidata(path, nd); - dget(dentry); - } - mntget(path->mnt); + if (path->mnt == nd->path.mnt) + mntget(nd->path.mnt); nd->last_type = LAST_BIND; *p = dentry->d_inode->i_op->follow_link(dentry, nd); error = PTR_ERR(*p); -- 1.6.3.3
WARNING: multiple messages have this Message-ID (diff)
From: Valerie Aurora <vaurora@redhat.com> To: Alexander Viro <viro@zeniv.linux.org.uk> Cc: autofs@linux.kernel.org, Miklos Szeredi <miklos@szeredi.hu>, linux-kernel@vger.kernel.org, Christoph Hellwig <hch@infradead.org>, Valerie Aurora <vaurora@redhat.com>, Alexander Viro <viro@zeniv.linux.org.uk>, linux-fsdevel@vger.kernel.org, Jan Blunck <jblunck@suse.de> Subject: [PATCH 04/38] autofs4: Save autofs trigger's vfsmount in super block info Date: Fri, 25 Jun 2010 12:04:54 -0700 [thread overview] Message-ID: <1277492728-11446-5-git-send-email-vaurora@redhat.com> (raw) In-Reply-To: <1277492728-11446-1-git-send-email-vaurora@redhat.com> From: Jan Blunck <jblunck@suse.de> XXX - This is broken and included just to make union mounts work. See discussion at: http://kerneltrap.org/mailarchive/linux-fsdevel/2010/1/15/6708053/thread Original commit message: This is a bugfix/replacement for commit 051d381259eb57d6074d02a6ba6e90e744f1a29f: During a path walk if an autofs trigger is mounted on a dentry, when the follow_link method is called, the nameidata struct contains the vfsmount and mountpoint dentry of the parent mount while the dentry that is passed in is the root of the autofs trigger mount. I believe it is impossible to get the vfsmount of the trigger mount, within the follow_link method, when only the parent vfsmount and the root dentry of the trigger mount are known. The solution in this commit was to replace the path embedded in the parent's nameidata with the path of the link itself in __do_follow_link(). This is a relatively harmless misuse of the field, but union mounts ran into a bug during follow_link() caused by the nameidata containing the wrong path (we count on it being what it is all other places - the path of the parent). A cleaner and easier to understand solution is to save the necessary vfsmount in the autofs superblock info when it is mounted. Then we can easily update the vfsmount in autofs4_follow_link(). Signed-off-by: Jan Blunck <jblunck@suse.de> Signed-off-by: Valerie Aurora <vaurora@redhat.com> Acked-by: Ian Kent <raven@themaw.net> Cc: autofs@linux.kernel.org Cc: Alexander Viro <viro@zeniv.linux.org.uk> --- fs/autofs4/autofs_i.h | 1 + fs/autofs4/init.c | 11 ++++++++++- fs/autofs4/root.c | 6 ++++++ fs/namei.c | 7 ++----- 4 files changed, 19 insertions(+), 6 deletions(-) diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h index 3d283ab..de3af64 100644 --- a/fs/autofs4/autofs_i.h +++ b/fs/autofs4/autofs_i.h @@ -133,6 +133,7 @@ struct autofs_sb_info { int reghost_enabled; int needs_reghost; struct super_block *sb; + struct vfsmount *mnt; struct mutex wq_mutex; spinlock_t fs_lock; struct autofs_wait_queue *queues; /* Wait queue pointer */ diff --git a/fs/autofs4/init.c b/fs/autofs4/init.c index 9722e4b..5e0dcd7 100644 --- a/fs/autofs4/init.c +++ b/fs/autofs4/init.c @@ -17,7 +17,16 @@ static int autofs_get_sb(struct file_system_type *fs_type, int flags, const char *dev_name, void *data, struct vfsmount *mnt) { - return get_sb_nodev(fs_type, flags, data, autofs4_fill_super, mnt); + struct autofs_sb_info *sbi; + int ret; + + ret = get_sb_nodev(fs_type, flags, data, autofs4_fill_super, mnt); + if (ret) + return ret; + + sbi = autofs4_sbi(mnt->mnt_sb); + sbi->mnt = mnt; + return 0; } static struct file_system_type autofs_fs_type = { diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c index e8e5e63..c41e01d 100644 --- a/fs/autofs4/root.c +++ b/fs/autofs4/root.c @@ -219,6 +219,12 @@ static void *autofs4_follow_link(struct dentry *dentry, struct nameidata *nd) DPRINTK("dentry=%p %.*s oz_mode=%d nd->flags=%d", dentry, dentry->d_name.len, dentry->d_name.name, oz_mode, nd->flags); + + dput(nd->path.dentry); + mntput(nd->path.mnt); + nd->path.mnt = mntget(sbi->mnt); + nd->path.dentry = dget(dentry); + /* * For an expire of a covered direct or offset mount we need * to break out of follow_down() at the autofs mount trigger diff --git a/fs/namei.c b/fs/namei.c index 3b43c48..f731108 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -538,11 +538,8 @@ __do_follow_link(struct path *path, struct nameidata *nd, void **p) touch_atime(path->mnt, dentry); nd_set_link(nd, NULL); - if (path->mnt != nd->path.mnt) { - path_to_nameidata(path, nd); - dget(dentry); - } - mntget(path->mnt); + if (path->mnt == nd->path.mnt) + mntget(nd->path.mnt); nd->last_type = LAST_BIND; *p = dentry->d_inode->i_op->follow_link(dentry, nd); error = PTR_ERR(*p); -- 1.6.3.3
next prev parent reply other threads:[~2010-06-25 19:06 UTC|newest] Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top 2010-06-25 19:04 [PATCH 00/38] Union mounts - multiple layers and submounts Valerie Aurora 2010-06-25 19:04 ` [PATCH 01/38] VFS: Comment follow_mount() and friends Valerie Aurora 2010-06-25 19:04 ` [PATCH 02/38] VFS: Make lookup_hash() return a struct path Valerie Aurora 2010-06-25 19:04 ` [PATCH 03/38] VFS: Add read-only users count to superblock Valerie Aurora 2010-06-25 19:04 ` Valerie Aurora [this message] 2010-06-25 19:04 ` [PATCH 04/38] autofs4: Save autofs trigger's vfsmount in super block info Valerie Aurora 2010-06-25 19:04 ` [PATCH 05/38] whiteout/NFSD: Don't return information about whiteouts to userspace Valerie Aurora 2010-06-25 19:04 ` [PATCH 06/38] whiteout: Add vfs_whiteout() and whiteout inode operation Valerie Aurora 2010-06-25 19:04 ` [PATCH 07/38] whiteout: Set S_OPAQUE inode flag when creating directories Valerie Aurora 2010-06-25 19:04 ` [PATCH 08/38] whiteout: Allow removal of a directory with whiteouts Valerie Aurora 2010-06-25 19:04 ` [PATCH 09/38] whiteout: tmpfs whiteout support Valerie Aurora 2010-06-25 19:04 ` Valerie Aurora 2010-06-25 19:05 ` [PATCH 10/38] whiteout: Split of ext2_append_link() from ext2_add_link() Valerie Aurora 2010-06-25 19:05 ` [PATCH 11/38] whiteout: ext2 whiteout support Valerie Aurora 2010-06-25 19:05 ` [PATCH 12/38] whiteout: jffs2 " Valerie Aurora 2010-06-25 19:05 ` Valerie Aurora 2010-06-25 19:05 ` Valerie Aurora 2010-06-25 19:05 ` [PATCH 13/38] fallthru: Basic fallthru definitions Valerie Aurora 2010-06-25 19:05 ` [PATCH 14/38] fallthru: ext2 fallthru support Valerie Aurora 2010-06-25 19:05 ` [PATCH 15/38] fallthru: jffs2 " Valerie Aurora 2010-06-25 19:05 ` Valerie Aurora 2010-06-25 19:05 ` Valerie Aurora 2010-06-25 19:05 ` [PATCH 16/38] fallthru: tmpfs " Valerie Aurora 2010-06-25 19:05 ` [PATCH 17/38] union-mount: Union mounts documentation Valerie Aurora 2010-06-25 19:05 ` [PATCH 18/38] union-mount: Introduce MNT_UNION and MS_UNION flags Valerie Aurora 2010-06-25 19:05 ` [PATCH 19/38] union-mount: Introduce union_dir structure and basic operations Valerie Aurora 2010-06-25 19:05 ` [PATCH 20/38] union-mount: Free union dirs on removal from dcache Valerie Aurora 2010-06-25 19:05 ` [PATCH 21/38] union-mount: Support for mounting union mount file systems Valerie Aurora 2010-06-25 19:05 ` [PATCH 22/38] union-mount: Implement union lookup Valerie Aurora 2010-06-25 19:05 ` [PATCH 23/38] union-mount: Call do_whiteout() on unlink and rmdir in unions Valerie Aurora 2010-06-25 19:05 ` [PATCH 24/38] union-mount: Copy up directory entries on first readdir() Valerie Aurora 2010-06-25 19:05 ` [PATCH 25/38] VFS: Split inode_permission() and create path_permission() Valerie Aurora 2010-06-25 19:05 ` [PATCH 26/38] VFS: Create user_path_nd() to lookup both parent and target Valerie Aurora 2010-06-25 19:05 ` [PATCH 27/38] union-mount: In-kernel file copyup routines Valerie Aurora 2010-06-25 19:05 ` [PATCH 28/38] union-mount: Implement union-aware access()/faccessat() Valerie Aurora 2010-06-25 19:05 ` [PATCH 29/38] union-mount: Implement union-aware link() Valerie Aurora 2010-06-25 19:05 ` [PATCH 30/38] union-mount: Implement union-aware rename() Valerie Aurora 2010-06-25 19:05 ` [PATCH 31/38] union-mount: Implement union-aware writable open() Valerie Aurora 2010-06-25 19:05 ` [PATCH 32/38] union-mount: Implement union-aware chown() Valerie Aurora 2010-06-25 19:05 ` [PATCH 33/38] union-mount: Implement union-aware truncate() Valerie Aurora 2010-06-25 19:05 ` [PATCH 34/38] union-mount: Implement union-aware chmod()/fchmodat() Valerie Aurora 2010-06-25 19:05 ` [PATCH 35/38] union-mount: Implement union-aware lchown() Valerie Aurora 2010-06-25 19:05 ` [PATCH 36/38] union-mount: Implement union-aware utimensat() Valerie Aurora 2010-06-25 19:05 ` [PATCH 37/38] union-mount: Implement union-aware setxattr() Valerie Aurora 2010-06-25 19:05 ` [PATCH 38/38] union-mount: Implement union-aware lsetxattr() Valerie Aurora -- strict thread matches above, loose matches on Subject: below -- 2010-08-06 22:34 [PATCH 00/38] VFS union mounts - Add MS_FALLTHRU Valerie Aurora 2010-08-06 22:34 ` [PATCH 04/38] autofs4: Save autofs trigger's vfsmount in super block info Valerie Aurora 2010-08-06 22:34 ` Valerie Aurora 2010-06-15 18:39 [PATCH 00/38] Union mounts - union stack as linked list Valerie Aurora 2010-06-15 18:39 ` [PATCH 04/38] autofs4: Save autofs trigger's vfsmount in super block info Valerie Aurora
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