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Subject[PATCH 5/7] vfs: add prepend_path() helper
From: Miklos Szeredi <mszeredi@suse.cz>

Split off prepend_path() from __d_path(). This new helper takes an
end-of-buffer pointer and buffer-length pointer just like the other
prepend_* functions. Move the " (deleted)" postfix out to __d_path().

This patch doesn't change any functionality but paves the way for the
following patches.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
---
fs/dcache.c | 94 +++++++++++++++++++++++++++++++++++++-----------------------
1 file changed, 58 insertions(+), 36 deletions(-)
Index: linux-2.6/fs/dcache.c
===================================================================
--- linux-2.6.orig/fs/dcache.c 2010-07-06 18:08:12.000000000 +0200
+++ linux-2.6/fs/dcache.c 2010-07-06 18:08:16.000000000 +0200
@@ -1903,48 +1903,30 @@ static int prepend_name(char **buffer, i
}

/**
- * __d_path - return the path of a dentry
+ * Prepend path string to a buffer
+ *
* @path: the dentry/vfsmount to report
* @root: root vfsmnt/dentry (may be modified by this function)
- * @buffer: buffer to return value in
- * @buflen: buffer length
+ * @buffer: pointer to the end of the buffer
+ * @buflen: pointer to buffer length
*
- * Convert a dentry into an ASCII path name. If the entry has been deleted
- * the string " (deleted)" is appended. Note that this is ambiguous.
- *
- * Returns a pointer into the buffer or an error code if the
- * path was too long.
- *
- * "buflen" should be positive. Caller holds the dcache_lock.
+ * Caller holds the dcache_lock.
*
* If path is not reachable from the supplied root, then the value of
* root is changed (without modifying refcounts).
*/
-char *__d_path(const struct path *path, struct path *root,
- char *buffer, int buflen)
+static int prepend_path(const struct path *path, struct path *root,
+ char **buffer, int *buflen)
{
struct dentry *dentry = path->dentry;
struct vfsmount *vfsmnt = path->mnt;
- char *end = buffer + buflen;
- char *retval;
+ bool slash = false;
+ int error = 0;

spin_lock(&vfsmount_lock);
- prepend(&end, &buflen, "\0", 1);
- if (d_unlinked(dentry) &&
- (prepend(&end, &buflen, " (deleted)", 10) != 0))
- goto Elong;
-
- if (buflen < 1)
- goto Elong;
- /* Get '/' right */
- retval = end-1;
- *retval = '/';
-
- for (;;) {
+ while (dentry != root->dentry || vfsmnt != root->mnt) {
struct dentry * parent;

- if (dentry == root->dentry && vfsmnt == root->mnt)
- break;
if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
/* Global root? */
if (vfsmnt->mnt_parent == vfsmnt) {
@@ -1956,16 +1938,22 @@ char *__d_path(const struct path *path,
}
parent = dentry->d_parent;
prefetch(parent);
- if ((prepend_name(&end, &buflen, &dentry->d_name) != 0) ||
- (prepend(&end, &buflen, "/", 1) != 0))
- goto Elong;
- retval = end;
+ error = prepend_name(buffer, buflen, &dentry->d_name);
+ if (!error)
+ error = prepend(buffer, buflen, "/", 1);
+ if (error)
+ break;
+
+ slash = true;
dentry = parent;
}

out:
+ if (!error && !slash)
+ error = prepend(buffer, buflen, "/", 1);
+
spin_unlock(&vfsmount_lock);
- return retval;
+ return error;

global_root:
/*
@@ -1980,10 +1968,44 @@ global_root:
root->mnt = vfsmnt;
root->dentry = dentry;
goto out;
+}

-Elong:
- retval = ERR_PTR(-ENAMETOOLONG);
- goto out;
+/**
+ * __d_path - return the path of a dentry
+ * @path: the dentry/vfsmount to report
+ * @root: root vfsmnt/dentry (may be modified by this function)
+ * @buffer: buffer to return value in
+ * @buflen: buffer length
+ *
+ * Convert a dentry into an ASCII path name. If the entry has been deleted
+ * the string " (deleted)" is appended. Note that this is ambiguous.
+ *
+ * Returns a pointer into the buffer or an error code if the
+ * path was too long.
+ *
+ * "buflen" should be positive. Caller holds the dcache_lock.
+ *
+ * If path is not reachable from the supplied root, then the value of
+ * root is changed (without modifying refcounts).
+ */
+char *__d_path(const struct path *path, struct path *root,
+ char *buf, int buflen)
+{
+ char *res = buf + buflen;
+ int error;
+
+ prepend(&res, &buflen, "\0", 1);
+ if (d_unlinked(path->dentry)) {
+ error = prepend(&res, &buflen, " (deleted)", 10);
+ if (error)
+ return ERR_PTR(error);
+ }
+
+ error = prepend_path(path, root, &res, &buflen);
+ if (error)
+ return ERR_PTR(error);
+
+ return res;
}

/**
--


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