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authorJeff Mahoney <jeffm@jeffreymahoney.com>2010-03-19 15:35:46 -0400
committerTyler Hicks <tyhicks@linux.vnet.ibm.com>2010-04-19 14:42:13 -0500
commit133b8f9d632cc23715c6d72d1c5ac449e054a12a (patch)
tree4559634958e6da3f7a3e2b5ae1229b9e3924d5fa
parentcfce08c6bdfb20ade979284e55001ca1f100ed51 (diff)
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ecryptfs: fix use with tmpfs by removing d_drop from ecryptfs_destroy_inode
Since tmpfs has no persistent storage, it pins all its dentries in memory so they have d_count=1 when other file systems would have d_count=0. ->lookup is only used to create new dentries. If the caller doesn't instantiate it, it's freed immediately at dput(). ->readdir reads directly from the dcache and depends on the dentries being hashed. When an ecryptfs mount is mounted, it associates the lower file and dentry with the ecryptfs files as they're accessed. When it's umounted and destroys all the in-memory ecryptfs inodes, it fput's the lower_files and d_drop's the lower_dentries. Commit 4981e081 added this and a d_delete in 2008 and several months later commit caeeeecf removed the d_delete. I believe the d_drop() needs to be removed as well. The d_drop effectively hides any file that has been accessed via ecryptfs from the underlying tmpfs since it depends on it being hashed for it to be accessible. I've removed the d_drop on my development node and see no ill effects with basic testing on both tmpfs and persistent storage. As a side effect, after ecryptfs d_drops the dentries on tmpfs, tmpfs BUGs on umount. This is due to the dentries being unhashed. tmpfs->kill_sb is kill_litter_super which calls d_genocide to drop the reference pinning the dentry. It skips unhashed and negative dentries, but shrink_dcache_for_umount_subtree doesn't. Since those dentries still have an elevated d_count, we get a BUG(). This patch removes the d_drop call and fixes both issues. This issue was reported at: https://bugzilla.novell.com/show_bug.cgi?id=567887 Reported-by: Árpád Bíró <biroa@demasz.hu> Signed-off-by: Jeff Mahoney <jeffm@suse.com> Cc: Dustin Kirkland <kirkland@canonical.com> Cc: stable@kernel.org Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>
-rw-r--r--fs/ecryptfs/super.c1
1 files changed, 0 insertions, 1 deletions
diff --git a/fs/ecryptfs/super.c b/fs/ecryptfs/super.c
index b15a43a80ab..1a037f77aa5 100644
--- a/fs/ecryptfs/super.c
+++ b/fs/ecryptfs/super.c
@@ -85,7 +85,6 @@ static void ecryptfs_destroy_inode(struct inode *inode)
if (lower_dentry->d_inode) {
fput(inode_info->lower_file);
inode_info->lower_file = NULL;
- d_drop(lower_dentry);
}
}
ecryptfs_destroy_crypt_stat(&inode_info->crypt_stat);