Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755053AbZJUTUg (ORCPT ); Wed, 21 Oct 2009 15:20:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755032AbZJUTUe (ORCPT ); Wed, 21 Oct 2009 15:20:34 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38006 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754935AbZJUTUa (ORCPT ); Wed, 21 Oct 2009 15:20:30 -0400 From: Valerie Aurora To: Jan Blunck , Alexander Viro , Christoph Hellwig , Andy Whitcroft , Scott James Remnant , Sandu Popa Marius , Jan Rekorajski , "J. R. Okajima" , Arnd Bergmann , Vladimir Dronnikov , Felix Fietkau Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Jan Blunck , David Woodhouse Subject: [PATCH 10/41] whiteout: Add vfs_whiteout() and whiteout inode operation Date: Wed, 21 Oct 2009 12:19:08 -0700 Message-Id: <1256152779-10054-11-git-send-email-vaurora@redhat.com> In-Reply-To: <1256152779-10054-10-git-send-email-vaurora@redhat.com> References: <1256152779-10054-1-git-send-email-vaurora@redhat.com> <1256152779-10054-2-git-send-email-vaurora@redhat.com> <1256152779-10054-3-git-send-email-vaurora@redhat.com> <1256152779-10054-4-git-send-email-vaurora@redhat.com> <1256152779-10054-5-git-send-email-vaurora@redhat.com> <1256152779-10054-6-git-send-email-vaurora@redhat.com> <1256152779-10054-7-git-send-email-vaurora@redhat.com> <1256152779-10054-8-git-send-email-vaurora@redhat.com> <1256152779-10054-9-git-send-email-vaurora@redhat.com> <1256152779-10054-10-git-send-email-vaurora@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6879 Lines: 211 From: Jan Blunck Simply white-out a given directory entry. This functionality is usually used in the sense of unlink. Therefore the given dentry can still be in-use and contains an in-use inode. The filesystems inode operation has to do what unlink or rmdir would in that case. Since the dentry still might be in-use we have to provide a fresh unhashed dentry that is used as the whiteout dentry instead. The given dentry is dropped and the whiteout dentry is rehashed instead. Signed-off-by: Jan Blunck Signed-off-by: David Woodhouse Signed-off-by: Valerie Aurora --- fs/dcache.c | 4 +- fs/namei.c | 104 ++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/dcache.h | 6 +++ include/linux/fs.h | 3 + 4 files changed, 116 insertions(+), 1 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index 3415e9e..0fcae4b 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1076,8 +1076,10 @@ struct dentry *d_alloc_name(struct dentry *parent, const char *name) /* the caller must hold dcache_lock */ static void __d_instantiate(struct dentry *dentry, struct inode *inode) { - if (inode) + if (inode) { + dentry->d_flags &= ~DCACHE_WHITEOUT; list_add(&dentry->d_alias, &inode->i_dentry); + } dentry->d_inode = inode; fsnotify_d_instantiate(dentry, inode); } diff --git a/fs/namei.c b/fs/namei.c index 46cf1cb..d2fc8c9 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -2169,6 +2169,110 @@ SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode) return sys_mkdirat(AT_FDCWD, pathname, mode); } + +/* Checks on the victim for whiteout */ +static inline int may_whiteout(struct inode *dir, struct dentry *victim, + int isdir) +{ + int err; + + /* from may_create() */ + if (IS_DEADDIR(dir)) + return -ENOENT; + err = inode_permission(dir, MAY_WRITE | MAY_EXEC); + if (err) + return err; + + /* from may_delete() */ + if (IS_APPEND(dir)) + return -EPERM; + if (!victim->d_inode) + return 0; + if (check_sticky(dir, victim->d_inode) || + IS_APPEND(victim->d_inode) || + IS_IMMUTABLE(victim->d_inode)) + return -EPERM; + if (isdir) { + if (!S_ISDIR(victim->d_inode->i_mode)) + return -ENOTDIR; + if (IS_ROOT(victim)) + return -EBUSY; + } else if (S_ISDIR(victim->d_inode->i_mode)) + return -EISDIR; + if (victim->d_flags & DCACHE_NFSFS_RENAMED) + return -EBUSY; + return 0; +} + +/** + * vfs_whiteout: creates a white-out for the given directory entry + * @dir: parent inode + * @dentry: directory entry to white-out + * + * Simply white-out a given directory entry. This functionality is usually used + * in the sense of unlink. Therefore the given dentry can still be in-use and + * contains an in-use inode. The filesystem has to do what unlink or rmdir + * would in that case. Since the dentry still might be in-use we have to + * provide a fresh unhashed dentry that whiteout can fill the new inode into. + * In that case the given dentry is dropped and the fresh dentry containing the + * whiteout is rehashed instead. If the given dentry is unused, the whiteout + * inode is instantiated into it instead. + * + * After this returns with success, don't make any assumptions about the inode. + * Just dput() it dentry. + */ +int vfs_whiteout(struct inode *dir, struct dentry *dentry, int isdir) +{ + int err; + struct inode *old_inode = dentry->d_inode; + struct dentry *parent, *whiteout; + + err = may_whiteout(dir, dentry, isdir); + if (err) + return err; + + BUG_ON(dentry->d_parent->d_inode != dir); + + if (!dir->i_op || !dir->i_op->whiteout) + return -EOPNOTSUPP; + + if (old_inode) { + vfs_dq_init(dir); + + mutex_lock(&old_inode->i_mutex); + if (isdir) + dentry_unhash(dentry); + if (d_mountpoint(dentry)) + err = -EBUSY; + else { + if (isdir) + err = security_inode_rmdir(dir, dentry); + else + err = security_inode_unlink(dir, dentry); + } + } + + parent = dget_parent(dentry); + whiteout = d_alloc_name(parent, dentry->d_name.name); + + if (!err) + err = dir->i_op->whiteout(dir, dentry, whiteout); + + if (old_inode) { + mutex_unlock(&old_inode->i_mutex); + if (!err) { + fsnotify_link_count(old_inode); + d_delete(dentry); + } + if (isdir) + dput(dentry); + } + + dput(whiteout); + dput(parent); + return err; +} + /* * We try to drop the dentry early: we should have * a usage count of 2 if we're the only user of this diff --git a/include/linux/dcache.h b/include/linux/dcache.h index 30b93b2..7648b49 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -183,6 +183,7 @@ d_iput: no no no yes #define DCACHE_INOTIFY_PARENT_WATCHED 0x0020 /* Parent inode is watched by inotify */ #define DCACHE_COOKIE 0x0040 /* For use by dcookie subsystem */ +#define DCACHE_WHITEOUT 0x0080 /* This negative dentry is a whiteout */ #define DCACHE_FSNOTIFY_PARENT_WATCHED 0x0080 /* Parent inode is watched by some fsnotify listener */ @@ -358,6 +359,11 @@ static inline int d_unlinked(struct dentry *dentry) return d_unhashed(dentry) && !IS_ROOT(dentry); } +static inline int d_is_whiteout(struct dentry *dentry) +{ + return (dentry->d_flags & DCACHE_WHITEOUT); +} + static inline struct dentry *dget_parent(struct dentry *dentry) { struct dentry *ret; diff --git a/include/linux/fs.h b/include/linux/fs.h index 5fb7343..04a9870 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -205,6 +205,7 @@ struct inodes_stat_t { #define MS_KERNMOUNT (1<<22) /* this is a kern_mount call */ #define MS_I_VERSION (1<<23) /* Update inode I_version field */ #define MS_STRICTATIME (1<<24) /* Always perform atime updates */ +#define MS_WHITEOUT (1<<26) /* fs does support white-out filetype */ #define MS_ACTIVE (1<<30) #define MS_NOUSER (1<<31) @@ -1422,6 +1423,7 @@ extern int vfs_link(struct dentry *, struct inode *, struct dentry *); extern int vfs_rmdir(struct inode *, struct dentry *); extern int vfs_unlink(struct inode *, struct dentry *); extern int vfs_rename(struct inode *, struct dentry *, struct inode *, struct dentry *); +extern int vfs_whiteout(struct inode *, struct dentry *, int); /* * VFS dentry helper functions. @@ -1526,6 +1528,7 @@ struct inode_operations { int (*mkdir) (struct inode *,struct dentry *,int); int (*rmdir) (struct inode *,struct dentry *); int (*mknod) (struct inode *,struct dentry *,int,dev_t); + int (*whiteout) (struct inode *, struct dentry *, struct dentry *); int (*rename) (struct inode *, struct dentry *, struct inode *, struct dentry *); int (*readlink) (struct dentry *, char __user *,int); -- 1.6.3.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/