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Subject[PATCH 16 of 23] Unionfs: Handling of stale inodes
Date
From
From: Josef "Jeff" Sipek <jsipek@cs.sunysb.edu>

Provides nicer handling of stale inodes.

Signed-off-by: Josef "Jeff" Sipek <jsipek@cs.sunysb.edu>
Signed-off-by: David Quigley <dquigley@fsl.cs.sunysb.edu>
Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>

---
1 file changed, 114 insertions(+)
fs/unionfs/stale_inode.c | 114 ++++++++++++++++++++++++++++++++++++++++++++++
diff -r b601a3cced0e -r 766f19339624 fs/unionfs/stale_inode.c
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/fs/unionfs/stale_inode.c Sat Oct 07 00:46:19 2006 -0400
@@ -0,0 +1,114 @@
+/*
+ * Adpated from linux/fs/bad_inode.c
+ *
+ * Copyright (C) 1997, Stephen Tweedie
+ *
+ * Provide stub functions for "stale" inodes, a bit friendlier than the
+ * -EIO that bad_inode.c does.
+ */
+
+#include <linux/version.h>
+
+#include <linux/fs.h>
+#include <linux/stat.h>
+#include <linux/sched.h>
+
+static struct address_space_operations unionfs_stale_aops;
+
+/* declarations for "sparse */
+extern struct inode_operations stale_inode_ops;
+
+/*
+ * The follow_link operation is special: it must behave as a no-op
+ * so that a stale root inode can at least be unmounted. To do this
+ * we must dput() the base and return the dentry with a dget().
+ */
+static void *stale_follow_link(struct dentry *dent, struct nameidata *nd)
+{
+ return ERR_PTR(vfs_follow_link(nd, ERR_PTR(-ESTALE)));
+}
+
+static int return_ESTALE(void)
+{
+ return -ESTALE;
+}
+
+#define ESTALE_ERROR ((void *) (return_ESTALE))
+
+static struct file_operations stale_file_ops = {
+ .llseek = ESTALE_ERROR,
+ .read = ESTALE_ERROR,
+ .write = ESTALE_ERROR,
+ .readdir = ESTALE_ERROR,
+ .poll = ESTALE_ERROR,
+ .ioctl = ESTALE_ERROR,
+ .mmap = ESTALE_ERROR,
+ .open = ESTALE_ERROR,
+ .flush = ESTALE_ERROR,
+ .release = ESTALE_ERROR,
+ .fsync = ESTALE_ERROR,
+ .fasync = ESTALE_ERROR,
+ .lock = ESTALE_ERROR,
+};
+
+struct inode_operations stale_inode_ops = {
+ .create = ESTALE_ERROR,
+ .lookup = ESTALE_ERROR,
+ .link = ESTALE_ERROR,
+ .unlink = ESTALE_ERROR,
+ .symlink = ESTALE_ERROR,
+ .mkdir = ESTALE_ERROR,
+ .rmdir = ESTALE_ERROR,
+ .mknod = ESTALE_ERROR,
+ .rename = ESTALE_ERROR,
+ .readlink = ESTALE_ERROR,
+ .follow_link = stale_follow_link,
+ .truncate = ESTALE_ERROR,
+ .permission = ESTALE_ERROR,
+};
+
+/*
+ * When a filesystem is unable to read an inode due to an I/O error in
+ * its read_inode() function, it can call make_stale_inode() to return a
+ * set of stubs which will return ESTALE errors as required.
+ *
+ * We only need to do limited initialisation: all other fields are
+ * preinitialised to zero automatically.
+ */
+
+/**
+ * make_stale_inode - mark an inode stale due to an I/O error
+ * @inode: Inode to mark stale
+ *
+ * When an inode cannot be read due to a media or remote network
+ * failure this function makes the inode "stale" and causes I/O operations
+ * on it to fail from this point on.
+ */
+
+void make_stale_inode(struct inode *inode)
+{
+ inode->i_mode = S_IFREG;
+ inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+ inode->i_op = &stale_inode_ops;
+ inode->i_fop = &stale_file_ops;
+ inode->i_mapping->a_ops = &unionfs_stale_aops;
+}
+
+/*
+ * This tests whether an inode has been flagged as stale. The test uses
+ * &stale_inode_ops to cover the case of invalidated inodes as well as
+ * those created by make_stale_inode() above.
+ */
+
+/**
+ * is_stale_inode - is an inode errored
+ * @inode: inode to test
+ *
+ * Returns true if the inode in question has been marked as stale.
+ */
+
+int is_stale_inode(struct inode *inode)
+{
+ return (inode->i_op == &stale_inode_ops);
+}
+

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