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authorJohn Muir <john@jmuir.com>2011-12-06 21:50:06 +0100
committerMiklos Szeredi <mszeredi@suse.cz>2011-12-13 11:58:49 +0100
commit451d0f599934fd97faf54a5d7954b518e66192cb (patch)
tree6dd7a6fcdc8ff3bc50dec37b114c447b3b1d7ba1 /fs/fuse/dir.c
parentb18da0c56e9ff43a007b6c8e302c62e720964151 (diff)
downloadlinux-linaro-stable-451d0f599934fd97faf54a5d7954b518e66192cb.tar.gz
FUSE: Notifying the kernel of deletion.
Allows a FUSE file-system to tell the kernel when a file or directory is deleted. If the specified dentry has the specified inode number, the kernel will unhash it. The current 'fuse_notify_inval_entry' does not cause the kernel to clean up directories that are in use properly, and as a result the users of those directories see incorrect semantics from the file-system. The error condition seen when 'fuse_notify_inval_entry' is used to notify of a deleted directory is avoided when 'fuse_notify_delete' is used instead. The following scenario demonstrates the difference: 1. User A chdirs into 'testdir' and starts reading 'testfile'. 2. User B rm -rf 'testdir'. 3. User B creates 'testdir'. 4. User C chdirs into 'testdir'. If you run the above within the same machine on any file-system (including fuse file-systems), there is no problem: user C is able to chdir into the new testdir. The old testdir is removed from the dentry tree, but still open by user A. If operations 2 and 3 are performed via the network such that the fuse file-system uses one of the notify functions to tell the kernel that the nodes are gone, then the following error occurs for user C while user A holds the original directory open: muirj@empacher:~> ls /test/testdir ls: cannot access /test/testdir: No such file or directory The issue here is that the kernel still has a dentry for testdir, and so it is requesting the attributes for the old directory, while the file-system is responding that the directory no longer exists. If on the other hand, if the file-system can notify the kernel that the directory is deleted using the new 'fuse_notify_delete' function, then the above ls will find the new directory as expected. Signed-off-by: John Muir <john@jmuir.com> Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Diffstat (limited to 'fs/fuse/dir.c')
-rw-r--r--fs/fuse/dir.c32
1 files changed, 30 insertions, 2 deletions
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 344577933f62..bef8c3011d31 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -868,7 +868,7 @@ int fuse_update_attributes(struct inode *inode, struct kstat *stat,
}
int fuse_reverse_inval_entry(struct super_block *sb, u64 parent_nodeid,
- struct qstr *name)
+ u64 child_nodeid, struct qstr *name)
{
int err = -ENOTDIR;
struct inode *parent;
@@ -895,8 +895,36 @@ int fuse_reverse_inval_entry(struct super_block *sb, u64 parent_nodeid,
fuse_invalidate_attr(parent);
fuse_invalidate_entry(entry);
+
+ if (child_nodeid != 0 && entry->d_inode) {
+ mutex_lock(&entry->d_inode->i_mutex);
+ if (get_node_id(entry->d_inode) != child_nodeid) {
+ err = -ENOENT;
+ goto badentry;
+ }
+ if (d_mountpoint(entry)) {
+ err = -EBUSY;
+ goto badentry;
+ }
+ if (S_ISDIR(entry->d_inode->i_mode)) {
+ shrink_dcache_parent(entry);
+ if (!simple_empty(entry)) {
+ err = -ENOTEMPTY;
+ goto badentry;
+ }
+ entry->d_inode->i_flags |= S_DEAD;
+ }
+ dont_mount(entry);
+ clear_nlink(entry->d_inode);
+ err = 0;
+ badentry:
+ mutex_unlock(&entry->d_inode->i_mutex);
+ if (!err)
+ d_delete(entry);
+ } else {
+ err = 0;
+ }
dput(entry);
- err = 0;
unlock:
mutex_unlock(&parent->i_mutex);