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Date: Thu, 16 Sep 2010 15:12:06 -0700 From: Valerie Aurora <vaurora@...hat.com> To: Alexander Viro <viro@...iv.linux.org.uk> Cc: Miklos Szeredi <miklos@...redi.hu>, Christoph Hellwig <hch@...radead.org>, Andreas Gruenbacher <agruen@...e.de>, Nick Piggin <npiggin@...nel.dk>, linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org, Valerie Aurora <vaurora@...hat.com> Subject: [PATCH 15/34] union-mount: Add union_create_topmost_dir() Union mounts design requires that the topmost directory exist for every single directory at the time lookup completes. This is so that we don't have to double back and create a whole path's worth of directories whenever we copy up a file in a directory for the first time. This greatly simplifies locking and error handling. XXX - attributes of copied-up dir are wrong Signed-off-by: Valerie Aurora <vaurora@...hat.com> --- fs/union.c | 34 ++++++++++++++++++++++++++++++++++ fs/union.h | 3 +++ 2 files changed, 37 insertions(+), 0 deletions(-) diff --git a/fs/union.c b/fs/union.c index 45552f8..bc53066 100644 --- a/fs/union.c +++ b/fs/union.c @@ -93,3 +93,37 @@ int union_add_dir(struct path *topmost, struct path *lower, *path = *lower; return 0; } + +/** + * union_create_topmost_dir - Create a matching dir in the topmost file system + * + * @parent - parent of target on topmost layer + * @name - name of target + * @topmost - path of target on topmost layer + * @lower - path of source on lower layer + * + * As we lookup each directory on the lower layer of a union, we + * create a matching directory on the topmost layer if it does not + * already exist. + * + * XXX - owner is wrong, set credentials properly + */ + +int union_create_topmost_dir(struct path *parent, struct qstr *name, + struct path *topmost, struct path *lower) +{ + int mode = lower->dentry->d_inode->i_mode; + int res; + + BUG_ON(topmost->dentry->d_inode); + + res = mnt_want_write(parent->mnt); + if (res) + return res; + + res = vfs_mkdir(parent->dentry->d_inode, topmost->dentry, mode); + + mnt_drop_write(parent->mnt); + + return res; +} diff --git a/fs/union.h b/fs/union.h index bd03d67..1692803 100644 --- a/fs/union.h +++ b/fs/union.h @@ -53,6 +53,8 @@ struct union_stack { extern void d_free_unions(struct dentry *); extern int union_add_dir(struct path *, struct path *, unsigned int); +extern int union_create_topmost_dir(struct path *, struct qstr *, struct path *, + struct path *); static inline struct path *union_find_dir(struct dentry *dentry, unsigned int layer) { @@ -67,6 +69,7 @@ static inline struct path *union_find_dir(struct dentry *dentry, #define d_free_unions(x) do { } while (0) #define union_add_dir(x, y, z) ({ BUG(); (0); }) #define union_find_dir(x, y) ({ BUG(); (NULL); }) +#define union_create_topmost_dir(w, x, y, z) ({ BUG(); (0); }) #endif /* CONFIG_UNION_MOUNT */ #endif /* __KERNEL__ */ -- 1.6.3.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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