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authorJeff Layton <jlayton@redhat.com>2010-09-17 17:31:30 -0400
committerTrond Myklebust <Trond.Myklebust@netapp.com>2010-09-17 17:31:30 -0400
commit779c51795bfb35c2403c924b9de90ca9356bc693 (patch)
tree6bdd2e6896425b58df4ec457c583a15af21cb0c4 /fs/nfs/unlink.c
parente8582a8b96f329083b4da29aa87bc43cc0d80dd1 (diff)
downloadlinux-stericsson-779c51795bfb35c2403c924b9de90ca9356bc693.tar.gz
nfs: move nfs_sillyrename to unlink.c
...since that's where most of the sillyrenaming code lives. A comment block is added to the beginning as well to clarify how sillyrenaming works. Also, make nfs_async_unlink static as nfs_sillyrename is the only caller. Signed-off-by: Jeff Layton <jlayton@redhat.com> Reviewed-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Diffstat (limited to 'fs/nfs/unlink.c')
-rw-r--r--fs/nfs/unlink.c85
1 files changed, 84 insertions, 1 deletions
diff --git a/fs/nfs/unlink.c b/fs/nfs/unlink.c
index 2f84adaad427..c3ce865294f1 100644
--- a/fs/nfs/unlink.c
+++ b/fs/nfs/unlink.c
@@ -13,9 +13,12 @@
#include <linux/nfs_fs.h>
#include <linux/sched.h>
#include <linux/wait.h>
+#include <linux/namei.h>
#include "internal.h"
#include "nfs4_fs.h"
+#include "iostat.h"
+#include "delegation.h"
struct nfs_unlinkdata {
struct hlist_node list;
@@ -244,7 +247,7 @@ void nfs_unblock_sillyrename(struct dentry *dentry)
* @dir: parent directory of dentry
* @dentry: dentry to unlink
*/
-int
+static int
nfs_async_unlink(struct inode *dir, struct dentry *dentry)
{
struct nfs_unlinkdata *data;
@@ -303,3 +306,83 @@ nfs_complete_unlink(struct dentry *dentry, struct inode *inode)
if (data != NULL && (NFS_STALE(inode) || !nfs_call_unlink(dentry, data)))
nfs_free_unlinkdata(data);
}
+
+/**
+ * nfs_sillyrename - Perform a silly-rename of a dentry
+ * @dir: inode of directory that contains dentry
+ * @dentry: dentry to be sillyrenamed
+ *
+ * NFSv2/3 is stateless and the server doesn't know when the client is
+ * holding a file open. To prevent application problems when a file is
+ * unlinked while it's still open, the client performs a "silly-rename".
+ * That is, it renames the file to a hidden file in the same directory,
+ * and only performs the unlink once the last reference to it is put.
+ *
+ * The final cleanup is done during dentry_iput.
+ */
+int
+nfs_sillyrename(struct inode *dir, struct dentry *dentry)
+{
+ static unsigned int sillycounter;
+ const int fileidsize = sizeof(NFS_FILEID(dentry->d_inode))*2;
+ const int countersize = sizeof(sillycounter)*2;
+ const int slen = sizeof(".nfs")+fileidsize+countersize-1;
+ char silly[slen+1];
+ struct qstr qsilly;
+ struct dentry *sdentry;
+ int error = -EIO;
+
+ dfprintk(VFS, "NFS: silly-rename(%s/%s, ct=%d)\n",
+ dentry->d_parent->d_name.name, dentry->d_name.name,
+ atomic_read(&dentry->d_count));
+ nfs_inc_stats(dir, NFSIOS_SILLYRENAME);
+
+ /*
+ * We don't allow a dentry to be silly-renamed twice.
+ */
+ error = -EBUSY;
+ if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
+ goto out;
+
+ sprintf(silly, ".nfs%*.*Lx",
+ fileidsize, fileidsize,
+ (unsigned long long)NFS_FILEID(dentry->d_inode));
+
+ /* Return delegation in anticipation of the rename */
+ nfs_inode_return_delegation(dentry->d_inode);
+
+ sdentry = NULL;
+ do {
+ char *suffix = silly + slen - countersize;
+
+ dput(sdentry);
+ sillycounter++;
+ sprintf(suffix, "%*.*x", countersize, countersize, sillycounter);
+
+ dfprintk(VFS, "NFS: trying to rename %s to %s\n",
+ dentry->d_name.name, silly);
+
+ sdentry = lookup_one_len(silly, dentry->d_parent, slen);
+ /*
+ * N.B. Better to return EBUSY here ... it could be
+ * dangerous to delete the file while it's in use.
+ */
+ if (IS_ERR(sdentry))
+ goto out;
+ } while (sdentry->d_inode != NULL); /* need negative lookup */
+
+ qsilly.name = silly;
+ qsilly.len = strlen(silly);
+ error = NFS_PROTO(dir)->rename(dir, &dentry->d_name, dir, &qsilly);
+ if (dentry->d_inode)
+ nfs_mark_for_revalidate(dentry->d_inode);
+ if (!error) {
+ nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
+ d_move(dentry, sdentry);
+ error = nfs_async_unlink(dir, dentry);
+ /* If we return 0 we don't unlink */
+ }
+ dput(sdentry);
+out:
+ return error;
+}