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@@ -13,9 +13,12 @@
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#include <linux/nfs_fs.h>
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#include <linux/sched.h>
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#include <linux/wait.h>
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+#include <linux/namei.h>
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#include "internal.h"
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#include "nfs4_fs.h"
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+#include "iostat.h"
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+#include "delegation.h"
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struct nfs_unlinkdata {
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struct hlist_node list;
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@@ -244,7 +247,7 @@ void nfs_unblock_sillyrename(struct dentry *dentry)
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* @dir: parent directory of dentry
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* @dentry: dentry to unlink
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*/
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-int
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+static int
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nfs_async_unlink(struct inode *dir, struct dentry *dentry)
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{
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struct nfs_unlinkdata *data;
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@@ -303,3 +306,83 @@ nfs_complete_unlink(struct dentry *dentry, struct inode *inode)
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if (data != NULL && (NFS_STALE(inode) || !nfs_call_unlink(dentry, data)))
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nfs_free_unlinkdata(data);
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}
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+
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+/**
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+ * nfs_sillyrename - Perform a silly-rename of a dentry
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+ * @dir: inode of directory that contains dentry
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+ * @dentry: dentry to be sillyrenamed
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+ *
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+ * NFSv2/3 is stateless and the server doesn't know when the client is
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+ * holding a file open. To prevent application problems when a file is
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+ * unlinked while it's still open, the client performs a "silly-rename".
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+ * That is, it renames the file to a hidden file in the same directory,
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+ * and only performs the unlink once the last reference to it is put.
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+ *
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+ * The final cleanup is done during dentry_iput.
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+ */
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+int
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+nfs_sillyrename(struct inode *dir, struct dentry *dentry)
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+{
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+ static unsigned int sillycounter;
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+ const int fileidsize = sizeof(NFS_FILEID(dentry->d_inode))*2;
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+ const int countersize = sizeof(sillycounter)*2;
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+ const int slen = sizeof(".nfs")+fileidsize+countersize-1;
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+ char silly[slen+1];
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+ struct qstr qsilly;
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+ struct dentry *sdentry;
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+ int error = -EIO;
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+
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+ dfprintk(VFS, "NFS: silly-rename(%s/%s, ct=%d)\n",
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+ dentry->d_parent->d_name.name, dentry->d_name.name,
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+ atomic_read(&dentry->d_count));
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+ nfs_inc_stats(dir, NFSIOS_SILLYRENAME);
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+
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+ /*
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+ * We don't allow a dentry to be silly-renamed twice.
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+ */
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+ error = -EBUSY;
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+ if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
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+ goto out;
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+
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+ sprintf(silly, ".nfs%*.*Lx",
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+ fileidsize, fileidsize,
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+ (unsigned long long)NFS_FILEID(dentry->d_inode));
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+
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+ /* Return delegation in anticipation of the rename */
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+ nfs_inode_return_delegation(dentry->d_inode);
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+
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+ sdentry = NULL;
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+ do {
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+ char *suffix = silly + slen - countersize;
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+
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+ dput(sdentry);
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+ sillycounter++;
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+ sprintf(suffix, "%*.*x", countersize, countersize, sillycounter);
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+
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+ dfprintk(VFS, "NFS: trying to rename %s to %s\n",
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+ dentry->d_name.name, silly);
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+
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+ sdentry = lookup_one_len(silly, dentry->d_parent, slen);
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+ /*
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+ * N.B. Better to return EBUSY here ... it could be
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+ * dangerous to delete the file while it's in use.
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+ */
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+ if (IS_ERR(sdentry))
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+ goto out;
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+ } while (sdentry->d_inode != NULL); /* need negative lookup */
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+
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+ qsilly.name = silly;
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+ qsilly.len = strlen(silly);
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+ error = NFS_PROTO(dir)->rename(dir, &dentry->d_name, dir, &qsilly);
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+ if (dentry->d_inode)
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+ nfs_mark_for_revalidate(dentry->d_inode);
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+ if (!error) {
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+ nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
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+ d_move(dentry, sdentry);
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+ error = nfs_async_unlink(dir, dentry);
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+ /* If we return 0 we don't unlink */
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+ }
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+ dput(sdentry);
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+out:
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+ return error;
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+}
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Jeff Layton