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https://gitlab.com/apparmor/apparmor
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d_namespace & minor cleanup patches
This commit is contained in:
John Johansen
206
kernel-patches/for-mainline/d_path-lazy-unmounts.diff
Normal file
206
kernel-patches/for-mainline/d_path-lazy-unmounts.diff
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@@ -0,0 +1,206 @@
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Index: linux-2.6/fs/dcache.c
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===================================================================
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--- linux-2.6.orig/fs/dcache.c
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+++ linux-2.6/fs/dcache.c
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@@ -1739,45 +1739,43 @@ shouldnt_be_hashed:
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* @rootmnt: vfsmnt to which the root dentry belongs
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* @buffer: buffer to return value in
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* @buflen: buffer length
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+ * @fail_deleted: what to return when hitting a deleted dentry
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*
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- * Convert a dentry into an ASCII path name. If the entry has been deleted
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- * the string " (deleted)" is appended. Note that this is ambiguous.
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+ * Convert a dentry into an ASCII path name. If the entry has been deleted,
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+ * then if @fail_deleted is true, ERR_PTR(-ENOENT) is returned. Otherwise,
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+ * the the string " (deleted)" is appended. Note that this is ambiguous.
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*
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- * Returns the buffer or an error code if the path was too long.
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- *
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- * "buflen" should be positive. Caller holds the dcache_lock.
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+ * Returns the buffer or an error code.
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*/
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-static char * __d_path( struct dentry *dentry, struct vfsmount *vfsmnt,
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- struct dentry *root, struct vfsmount *rootmnt,
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- char *buffer, int buflen)
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+static char *__d_path(struct dentry *dentry, struct vfsmount *vfsmnt,
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+ struct dentry *root, struct vfsmount *rootmnt,
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+ char *buffer, int buflen, int fail_deleted)
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{
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- char * end = buffer+buflen;
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- char * retval;
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+ char *end = buffer + buflen - 1;
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int namelen;
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- *--end = '\0';
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+ buffer = end;
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+ if (buflen < 2)
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+ return ERR_PTR(-ENAMETOOLONG);
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+ *end = '\0';
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buflen--;
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+
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+ spin_lock(&dcache_lock);
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if (!IS_ROOT(dentry) && d_unhashed(dentry)) {
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- buflen -= 10;
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- end -= 10;
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- if (buflen < 0)
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+ if (fail_deleted) {
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+ buffer = ERR_PTR(-ENOENT);
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+ goto out;
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+ }
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+ if (buflen < 10)
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goto Elong;
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- memcpy(end, " (deleted)", 10);
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+ buflen -= 10;
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+ buffer -= 10;
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+ memcpy(buffer, " (deleted)", 10);
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}
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-
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- if (buflen < 1)
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- goto Elong;
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- /* Get '/' right */
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- retval = end-1;
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- *retval = '/';
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-
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- for (;;) {
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+ while (dentry != root || vfsmnt != rootmnt) {
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struct dentry * parent;
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- if (dentry == root && vfsmnt == rootmnt)
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- break;
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if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
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- /* Global root? */
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spin_lock(&vfsmount_lock);
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if (vfsmnt->mnt_parent == vfsmnt) {
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spin_unlock(&vfsmount_lock);
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@@ -1791,33 +1789,49 @@ static char * __d_path( struct dentry *d
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parent = dentry->d_parent;
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prefetch(parent);
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namelen = dentry->d_name.len;
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- buflen -= namelen + 1;
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- if (buflen < 0)
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+ if (buflen <= namelen)
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goto Elong;
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- end -= namelen;
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- memcpy(end, dentry->d_name.name, namelen);
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- *--end = '/';
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- retval = end;
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+ buflen -= namelen + 1;
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+ buffer -= namelen;
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+ memcpy(buffer, dentry->d_name.name, namelen);
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+ *--buffer = '/';
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dentry = parent;
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}
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+ /* Get '/' right */
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+ if (buffer == end)
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+ *--buffer = '/';
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- return retval;
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+out:
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+ spin_unlock(&dcache_lock);
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+ return buffer;
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global_root:
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+ /*
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+ * We went past the (vfsmount, dentry) we were loking for and have
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+ * either hit a root dentry, a lazily unmounted dentry, or an
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+ * unconnected dentry. Make sure we won't return a pathname rooted
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+ * in '/'.
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+ */
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namelen = dentry->d_name.len;
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- buflen -= namelen;
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- if (buflen < 0)
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- goto Elong;
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- retval -= namelen-1; /* hit the slash */
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- memcpy(retval, dentry->d_name.name, namelen);
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- return retval;
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+ if (namelen == 1 && *dentry->d_name.name == '/') {
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+ if (buffer != end)
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+ buffer++;
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+ } else {
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+ if (buflen < namelen)
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+ goto Elong;
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+ buffer -= namelen;
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+ memcpy(buffer, dentry->d_name.name, namelen);
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+ }
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+ goto out;
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+
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Elong:
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- return ERR_PTR(-ENAMETOOLONG);
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+ buffer = ERR_PTR(-ENAMETOOLONG);
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+ goto out;
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}
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/* write full pathname into buffer and return start of pathname */
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-char * d_path(struct dentry *dentry, struct vfsmount *vfsmnt,
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- char *buf, int buflen)
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+char *d_path(struct dentry *dentry, struct vfsmount *vfsmnt, char *buf,
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+ int buflen)
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{
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char *res;
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struct vfsmount *rootmnt;
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@@ -1827,9 +1841,7 @@ char * d_path(struct dentry *dentry, str
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rootmnt = mntget(current->fs->rootmnt);
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root = dget(current->fs->root);
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read_unlock(¤t->fs->lock);
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- spin_lock(&dcache_lock);
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- res = __d_path(dentry, vfsmnt, root, rootmnt, buf, buflen);
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- spin_unlock(&dcache_lock);
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+ res = __d_path(dentry, vfsmnt, root, rootmnt, buf, buflen, 0);
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dput(root);
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mntput(rootmnt);
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return res;
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@@ -1855,10 +1867,10 @@ char * d_path(struct dentry *dentry, str
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*/
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asmlinkage long sys_getcwd(char __user *buf, unsigned long size)
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{
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- int error;
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+ int error, len;
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struct vfsmount *pwdmnt, *rootmnt;
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struct dentry *pwd, *root;
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- char *page = (char *) __get_free_page(GFP_USER);
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+ char *page = (char *) __get_free_page(GFP_USER), *cwd;
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if (!page)
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return -ENOMEM;
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@@ -1870,29 +1882,18 @@ asmlinkage long sys_getcwd(char __user *
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root = dget(current->fs->root);
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read_unlock(¤t->fs->lock);
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- error = -ENOENT;
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- /* Has the current directory has been unlinked? */
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- spin_lock(&dcache_lock);
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- if (pwd->d_parent == pwd || !d_unhashed(pwd)) {
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- unsigned long len;
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- char * cwd;
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-
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- cwd = __d_path(pwd, pwdmnt, root, rootmnt, page, PAGE_SIZE);
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- spin_unlock(&dcache_lock);
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-
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- error = PTR_ERR(cwd);
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- if (IS_ERR(cwd))
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- goto out;
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-
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- error = -ERANGE;
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- len = PAGE_SIZE + page - cwd;
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- if (len <= size) {
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- error = len;
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- if (copy_to_user(buf, cwd, len))
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- error = -EFAULT;
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- }
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- } else
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- spin_unlock(&dcache_lock);
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+ cwd = __d_path(pwd, pwdmnt, root, rootmnt, page, PAGE_SIZE, 1);
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+ error = PTR_ERR(cwd);
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+ if (IS_ERR(cwd))
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+ goto out;
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+
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+ error = -ERANGE;
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+ len = PAGE_SIZE + page - cwd;
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+ if (len <= size) {
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+ error = len;
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+ if (copy_to_user(buf, cwd, len))
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+ error = -EFAULT;
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+ }
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out:
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dput(pwd);
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