Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755300AbZJUTVj (ORCPT ); Wed, 21 Oct 2009 15:21:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755260AbZJUTVg (ORCPT ); Wed, 21 Oct 2009 15:21:36 -0400 Received: from mx1.redhat.com ([209.132.183.28]:23431 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755226AbZJUTVY (ORCPT ); Wed, 21 Oct 2009 15:21:24 -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 Subject: [PATCH 31/41] fallthru: Support for fallthru entries in union mount lookup Date: Wed, 21 Oct 2009 12:19:29 -0700 Message-Id: <1256152779-10054-32-git-send-email-vaurora@redhat.com> In-Reply-To: <1256152779-10054-31-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> <1256152779-10054-11-git-send-email-vaurora@redhat.com> <1256152779-10054-12-git-send-email-vaurora@redhat.com> <1256152779-10054-13-git-send-email-vaurora@redhat.com> <1256152779-10054-14-git-send-email-vaurora@redhat.com> <1256152779-10054-15-git-send-email-vaurora@redhat.com> <1256152779-10054-16-git-send-email-vaurora@redhat.com> <1256152779-10054-17-git-send-email-vaurora@redhat.com> <1256152779-10054-18-git-send-email-vaurora@redhat.com> <1256152779-10054-19-git-send-email-vaurora@redhat.com> <1256152779-10054-20-git-send-email-vaurora@redhat.com> <1256152779-10054-21-git-send-email-vaurora@redhat.com> <1256152779-10054-22-git-send-email-vaurora@redhat.com> <1256152779-10054-23-git-send-email-vaurora@redhat.com> <1256152779-10054-24-git-send-email-vaurora@redhat.com> <1256152779-10054-25-git-send-email-vaurora@redhat.com> <1256152779-10054-26-git-send-email-vaurora@redhat.com> <1256152779-10054-27-git-send-email-vaurora@redhat.com> <1256152779-10054-28-git-send-email-vaurora@redhat.com> <1256152779-10054-29-git-send-email-vaurora@redhat.com> <1256152779-10054-30-git-send-email-vaurora@redhat.com> <1256152779-10054-31-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: 6912 Lines: 200 A fallthru directory entry overrides the opaque flag for its parent directory (for this directory entry only). Before, we stopped building the union stack when we encountered an opaque directory; now we include directories below opaque directories in the union stack and check for opacity during lookup. Signed-off-by: Jan Blunck Signed-off-by: Valerie Aurora --- fs/dcache.c | 7 +++---- fs/namei.c | 59 +++++++++++++++++++++++++++++++++++++++++++++-------------- 2 files changed, 48 insertions(+), 18 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index d80a3bb..ca8a661 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1086,7 +1086,7 @@ struct dentry *d_alloc_name(struct dentry *parent, const char *name) static void __d_instantiate(struct dentry *dentry, struct inode *inode) { if (inode) { - dentry->d_flags &= ~DCACHE_WHITEOUT; + dentry->d_flags &= ~(DCACHE_WHITEOUT|DCACHE_FALLTHRU); list_add(&dentry->d_alias, &inode->i_dentry); } dentry->d_inode = inode; @@ -1638,9 +1638,8 @@ void d_delete(struct dentry * dentry) static void __d_rehash(struct dentry * entry, struct hlist_head *list) { - - entry->d_flags &= ~DCACHE_UNHASHED; - hlist_add_head_rcu(&entry->d_hash, list); + entry->d_flags &= ~DCACHE_UNHASHED; + hlist_add_head_rcu(&entry->d_hash, list); } static void _d_rehash(struct dentry * entry) diff --git a/fs/namei.c b/fs/namei.c index 8d95eb1..61e94aa 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -416,6 +416,28 @@ static struct dentry *cache_lookup(struct dentry *parent, struct qstr *name, return dentry; } +/* + * Theory of operation for opaque, whiteout, and fallthru: + * + * whiteout: Unconditionally stop lookup here - ENOENT + * + * opaque: Don't lookup in directories lower in the union stack + * + * fallthru: While looking up an entry, ignore the opaque flag for the + * current directory only. + * + * A union stack is a linked list of directory dentries which appear + * in the same place in the namespace. When constructing the union + * stack, we include directories below opaque directories so that we + * can properly handle fallthrus. All non-fallthru lookups have to + * check for the opaque flag on the parent directory and obey it. + * + * In general, the code pattern is to lookup the the topmost entry + * first (either the first visible non-negative dentry or a negative + * dentry in the topmost layer of the union), then build the union + * stack for the newly looked-up entry (if it is a directory). + */ + /** * __cache_lookup_topmost - lookup the topmost (non-)negative dentry * @@ -445,6 +467,10 @@ static int __cache_lookup_topmost(struct nameidata *nd, struct qstr *name, if (!dentry || (dentry->d_inode || d_is_whiteout(dentry))) return !dentry; + /* Keep going through opaque directories if we found a fallthru */ + if (IS_OPAQUE(nd->path.dentry->d_inode) && !d_is_fallthru(dentry)) + return !dentry; + /* look for the first non-negative or whiteout dentry */ while (follow_union_down(&nd->path.mnt, &nd->path.dentry)) { @@ -470,6 +496,10 @@ static int __cache_lookup_topmost(struct nameidata *nd, struct qstr *name, if (dentry->d_inode || d_is_whiteout(dentry)) goto out_dput; + /* Stop the lookup on opaque parent and non-fallthru child */ + if (IS_OPAQUE(nd->path.dentry->d_inode) && !d_is_fallthru(dentry)) + goto out_dput; + dput(dentry); } @@ -528,9 +558,6 @@ static int __cache_lookup_build_union(struct nameidata *nd, struct qstr *name, path_put(&last); last.dentry = dentry; last.mnt = mntget(nd->path.mnt); - - if (IS_OPAQUE(last.dentry->d_inode)) - break; } if (last.dentry != path->dentry) @@ -570,8 +597,7 @@ static int cache_lookup_union(struct nameidata *nd, struct qstr *name, /* only directories can be part of a union stack */ if (!path->dentry->d_inode || - !S_ISDIR(path->dentry->d_inode->i_mode) || - IS_OPAQUE(path->dentry->d_inode)) + !S_ISDIR(path->dentry->d_inode->i_mode)) goto out; /* Build the union stack for this part */ @@ -738,6 +764,9 @@ static int __real_lookup_topmost(struct nameidata *nd, struct qstr *name, if (path->dentry->d_inode || d_is_whiteout(path->dentry)) return 0; + if (IS_OPAQUE(nd->path.dentry->d_inode) && !d_is_fallthru(path->dentry)) + return 0; + while (follow_union_down(&nd->path.mnt, &nd->path.dentry)) { name->hash = full_name_hash(name->name, name->len); if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) { @@ -758,6 +787,9 @@ static int __real_lookup_topmost(struct nameidata *nd, struct qstr *name, goto out; } + if (IS_OPAQUE(nd->path.dentry->d_inode) && !d_is_fallthru(next.dentry)) + goto out; + dput(next.dentry); } out: @@ -817,9 +849,6 @@ static int __real_lookup_build_union(struct nameidata *nd, struct qstr *name, path_put(&last); last.dentry = next.dentry; last.mnt = mntget(next.mnt); - - if (IS_OPAQUE(last.dentry->d_inode)) - break; } if (last.dentry != path->dentry) @@ -841,8 +870,7 @@ static int real_lookup_union(struct nameidata *nd, struct qstr *name, /* only directories can be part of a union stack */ if (!path->dentry->d_inode || - !S_ISDIR(path->dentry->d_inode->i_mode) || - IS_OPAQUE(path->dentry->d_inode)) + !S_ISDIR(path->dentry->d_inode->i_mode)) goto out; /* Build the union stack for this part */ @@ -1128,7 +1156,7 @@ static int do_lookup(struct nameidata *nd, struct qstr *name, { int err; - if (IS_MNT_UNION(nd->path.mnt) && !IS_OPAQUE(nd->path.dentry->d_inode)) + if (IS_MNT_UNION(nd->path.mnt)) goto need_union_lookup; path->dentry = __d_lookup(nd->path.dentry, name); @@ -1679,6 +1707,9 @@ static int __hash_lookup_topmost(struct nameidata *nd, struct qstr *name, if (path->dentry->d_inode || d_is_whiteout(path->dentry)) return 0; + if (IS_OPAQUE(nd->path.dentry->d_inode) && !d_is_fallthru(path->dentry)) + return 0; + while (follow_union_down(&nd->path.mnt, &nd->path.dentry)) { name->hash = full_name_hash(name->name, name->len); if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) { @@ -1701,6 +1732,9 @@ static int __hash_lookup_topmost(struct nameidata *nd, struct qstr *name, goto out; } + if (IS_OPAQUE(nd->path.dentry->d_inode) && !d_is_fallthru(next.dentry)) + goto out; + dput(next.dentry); } out: @@ -1755,9 +1789,6 @@ static int __hash_lookup_build_union(struct nameidata *nd, struct qstr *name, path_put(&last); last.dentry = next.dentry; last.mnt = mntget(next.mnt); - - if (IS_OPAQUE(last.dentry->d_inode)) - break; } if (last.dentry != path->dentry) -- 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/