Re: [PATCH] make generic_acl slightly more generic

[Christoph Hellwig <hch@lst.de>]

respin, previous version lost some updates to shmem_fs.h to quilt..

-- 

Subject: [PATCH] make generic_acl slightly more generic
From: Christoph Hellwig <hch@lst.de>

Now that we cache the ACL pointers in the generic inode all the generic_acl
cruft can go away and generic_acl.c can directly implement xattr handlers
dealing with the full Posix ACL semantics for in-memory filesystems.

[Note: require the xattr handler prototype cleanup applied first]

Signed-off-by: Christoph Hellwig <hch@lst.de>

Index: linux-2.6/fs/generic_acl.c
===================================================================
--- linux-2.6.orig/fs/generic_acl.c	2009-09-23 10:01:18.480278413 -0300
+++ linux-2.6/fs/generic_acl.c	2009-09-26 11:54:15.159003290 -0300
@@ -1,62 +1,58 @@
 /*
- * fs/generic_acl.c
- *
  * (C) 2005 Andreas Gruenbacher <agruen@suse.de>
  *
  * This file is released under the GPL.
+ *
+ * Generic ACL support for in-memory filesystems.
  */
 
 #include <linux/sched.h>
 #include <linux/fs.h>
 #include <linux/generic_acl.h>
+#include <linux/posix_acl.h>
+#include <linux/posix_acl_xattr.h>
 
-/**
- * generic_acl_list  -  Generic xattr_handler->list() operation
- * @ops:	Filesystem specific getacl and setacl callbacks
- */
-size_t
-generic_acl_list(struct inode *inode, struct generic_acl_operations *ops,
-		 int type, char *list, size_t list_size)
+
+static size_t
+generic_acl_list(struct dentry *dentry, char *list, size_t list_size,
+		const char *name, size_t name_len, int type)
 {
 	struct posix_acl *acl;
-	const char *name;
+	const char *xname;
 	size_t size;
 
-	acl = ops->getacl(inode, type);
+	acl = get_cached_acl(dentry->d_inode, type);
 	if (!acl)
 		return 0;
 	posix_acl_release(acl);
 
-	switch(type) {
-		case ACL_TYPE_ACCESS:
-			name = POSIX_ACL_XATTR_ACCESS;
-			break;
-
-		case ACL_TYPE_DEFAULT:
-			name = POSIX_ACL_XATTR_DEFAULT;
-			break;
-
-		default:
-			return 0;
+	switch (type) {
+	case ACL_TYPE_ACCESS:
+		xname = POSIX_ACL_XATTR_ACCESS;
+		break;
+	case ACL_TYPE_DEFAULT:
+		xname = POSIX_ACL_XATTR_DEFAULT;
+		break;
+	default:
+		return 0;
 	}
-	size = strlen(name) + 1;
+	size = strlen(xname) + 1;
 	if (list && size <= list_size)
-		memcpy(list, name, size);
+		memcpy(list, xname, size);
 	return size;
 }
 
-/**
- * generic_acl_get  -  Generic xattr_handler->get() operation
- * @ops:	Filesystem specific getacl and setacl callbacks
- */
-int
-generic_acl_get(struct inode *inode, struct generic_acl_operations *ops,
-		int type, void *buffer, size_t size)
+static int
+generic_acl_get(struct dentry *dentry, const char *name, void *buffer,
+		     size_t size, int type)
 {
 	struct posix_acl *acl;
 	int error;
 
-	acl = ops->getacl(inode, type);
+	if (strcmp(name, "") != 0)
+		return -EINVAL;
+
+	acl = get_cached_acl(dentry->d_inode, type);
 	if (!acl)
 		return -ENODATA;
 	error = posix_acl_to_xattr(acl, buffer, size);
@@ -65,17 +61,16 @@ generic_acl_get(struct inode *inode, str
 	return error;
 }
 
-/**
- * generic_acl_set  -  Generic xattr_handler->set() operation
- * @ops:	Filesystem specific getacl and setacl callbacks
- */
-int
-generic_acl_set(struct inode *inode, struct generic_acl_operations *ops,
-		int type, const void *value, size_t size)
+static int
+generic_acl_set(struct dentry *dentry, const char *name, const void *value,
+		     size_t size, int flags, int type)
 {
+	struct inode *inode = dentry->d_inode;
 	struct posix_acl *acl = NULL;
 	int error;
 
+	if (strcmp(name, "") != 0)
+		return -EINVAL;
 	if (S_ISLNK(inode->i_mode))
 		return -EOPNOTSUPP;
 	if (!is_owner_or_cap(inode))
@@ -91,28 +86,27 @@ generic_acl_set(struct inode *inode, str
 		error = posix_acl_valid(acl);
 		if (error)
 			goto failed;
-		switch(type) {
-			case ACL_TYPE_ACCESS:
-				mode = inode->i_mode;
-				error = posix_acl_equiv_mode(acl, &mode);
-				if (error < 0)
-					goto failed;
-				inode->i_mode = mode;
-				if (error == 0) {
-					posix_acl_release(acl);
-					acl = NULL;
-				}
-				break;
-
-			case ACL_TYPE_DEFAULT:
-				if (!S_ISDIR(inode->i_mode)) {
-					error = -EINVAL;
-					goto failed;
-				}
-				break;
+		switch (type) {
+		case ACL_TYPE_ACCESS:
+			mode = inode->i_mode;
+			error = posix_acl_equiv_mode(acl, &mode);
+			if (error < 0)
+				goto failed;
+			inode->i_mode = mode;
+			if (error == 0) {
+				posix_acl_release(acl);
+				acl = NULL;
+			}
+			break;
+		case ACL_TYPE_DEFAULT:
+			if (!S_ISDIR(inode->i_mode)) {
+				error = -EINVAL;
+				goto failed;
+			}
+			break;
 		}
 	}
-	ops->setacl(inode, type, acl);
+	set_cached_acl(inode, type, acl);
 	error = 0;
 failed:
 	posix_acl_release(acl);
@@ -121,14 +115,12 @@ failed:
 
 /**
  * generic_acl_init  -  Take care of acl inheritance at @inode create time
- * @ops:	Filesystem specific getacl and setacl callbacks
  *
  * Files created inside a directory with a default ACL inherit the
  * directory's default ACL.
  */
 int
-generic_acl_init(struct inode *inode, struct inode *dir,
-		 struct generic_acl_operations *ops)
+generic_acl_init(struct inode *inode, struct inode *dir)
 {
 	struct posix_acl *acl = NULL;
 	mode_t mode = inode->i_mode;
@@ -136,7 +128,7 @@ generic_acl_init(struct inode *inode, st
 
 	inode->i_mode = mode & ~current_umask();
 	if (!S_ISLNK(inode->i_mode))
-		acl = ops->getacl(dir, ACL_TYPE_DEFAULT);
+		acl = get_cached_acl(dir, ACL_TYPE_DEFAULT);
 	if (acl) {
 		struct posix_acl *clone;
 
@@ -145,7 +137,7 @@ generic_acl_init(struct inode *inode, st
 			error = -ENOMEM;
 			if (!clone)
 				goto cleanup;
-			ops->setacl(inode, ACL_TYPE_DEFAULT, clone);
+			set_cached_acl(inode, ACL_TYPE_DEFAULT, clone);
 			posix_acl_release(clone);
 		}
 		clone = posix_acl_clone(acl, GFP_KERNEL);
@@ -156,7 +148,7 @@ generic_acl_init(struct inode *inode, st
 		if (error >= 0) {
 			inode->i_mode = mode;
 			if (error > 0)
-				ops->setacl(inode, ACL_TYPE_ACCESS, clone);
+				set_cached_acl(inode, ACL_TYPE_ACCESS, clone);
 		}
 		posix_acl_release(clone);
 	}
@@ -169,20 +161,19 @@ cleanup:
 
 /**
  * generic_acl_chmod  -  change the access acl of @inode upon chmod()
- * @ops:	FIlesystem specific getacl and setacl callbacks
  *
  * A chmod also changes the permissions of the owner, group/mask, and
  * other ACL entries.
  */
 int
-generic_acl_chmod(struct inode *inode, struct generic_acl_operations *ops)
+generic_acl_chmod(struct inode *inode)
 {
 	struct posix_acl *acl, *clone;
 	int error = 0;
 
 	if (S_ISLNK(inode->i_mode))
 		return -EOPNOTSUPP;
-	acl = ops->getacl(inode, ACL_TYPE_ACCESS);
+	acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
 	if (acl) {
 		clone = posix_acl_clone(acl, GFP_KERNEL);
 		posix_acl_release(acl);
@@ -190,8 +181,37 @@ generic_acl_chmod(struct inode *inode, s
 			return -ENOMEM;
 		error = posix_acl_chmod_masq(clone, inode->i_mode);
 		if (!error)
-			ops->setacl(inode, ACL_TYPE_ACCESS, clone);
+			set_cached_acl(inode, ACL_TYPE_ACCESS, clone);
 		posix_acl_release(clone);
 	}
 	return error;
 }
+
+int
+generic_check_acl(struct inode *inode, int mask)
+{
+	struct posix_acl *acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
+
+	if (acl) {
+		int error = posix_acl_permission(inode, acl, mask);
+		posix_acl_release(acl);
+		return error;
+	}
+	return -EAGAIN;
+}
+
+struct xattr_handler generic_acl_access_handler = {
+	.prefix = POSIX_ACL_XATTR_ACCESS,
+	.flags	= ACL_TYPE_ACCESS,
+	.list	= generic_acl_list,
+	.get	= generic_acl_get,
+	.set	= generic_acl_set,
+};
+
+struct xattr_handler generic_acl_default_handler = {
+	.prefix = POSIX_ACL_XATTR_DEFAULT,
+	.flags	= ACL_TYPE_DEFAULT,
+	.list	= generic_acl_list,
+	.get	= generic_acl_get,
+	.set	= generic_acl_set,
+};
Index: linux-2.6/include/linux/generic_acl.h
===================================================================
--- linux-2.6.orig/include/linux/generic_acl.h	2009-09-23 10:01:18.491253903 -0300
+++ linux-2.6/include/linux/generic_acl.h	2009-09-26 11:54:15.159003290 -0300
@@ -1,36 +1,15 @@
-/*
- * include/linux/generic_acl.h
- *
- * (C) 2005 Andreas Gruenbacher <agruen@suse.de>
- *
- * This file is released under the GPL.
- */
+#ifndef LINUX_GENERIC_ACL_H
+#define LINUX_GENERIC_ACL_H
 
-#ifndef GENERIC_ACL_H
-#define GENERIC_ACL_H
+#include <linux/xattr.h>
 
-#include <linux/posix_acl.h>
-#include <linux/posix_acl_xattr.h>
+struct inode;
 
-/**
- * struct generic_acl_operations  -  filesystem operations
- *
- * Filesystems must make these operations available to the generic
- * operations.
- */
-struct generic_acl_operations {
-	struct posix_acl *(*getacl)(struct inode *, int);
-	void (*setacl)(struct inode *, int, struct posix_acl *);
-};
+extern struct xattr_handler generic_acl_access_handler;
+extern struct xattr_handler generic_acl_default_handler;
 
-size_t generic_acl_list(struct inode *, struct generic_acl_operations *, int,
-			char *, size_t);
-int generic_acl_get(struct inode *, struct generic_acl_operations *, int,
-		    void *, size_t);
-int generic_acl_set(struct inode *, struct generic_acl_operations *, int,
-		    const void *, size_t);
-int generic_acl_init(struct inode *, struct inode *,
-		     struct generic_acl_operations *);
-int generic_acl_chmod(struct inode *, struct generic_acl_operations *);
+int generic_acl_init(struct inode *, struct inode *);
+int generic_acl_chmod(struct inode *);
+int generic_check_acl(struct inode *inode, int mask);
 
-#endif
+#endif /* LINUX_GENERIC_ACL_H */
Index: linux-2.6/include/linux/shmem_fs.h
===================================================================
--- linux-2.6.orig/include/linux/shmem_fs.h	2009-09-26 11:54:26.155261695 -0300
+++ linux-2.6/include/linux/shmem_fs.h	2009-09-26 11:54:58.230256457 -0300
@@ -41,20 +41,4 @@ static inline struct shmem_inode_info *S
 extern int init_tmpfs(void);
 extern int shmem_fill_super(struct super_block *sb, void *data, int silent);
 
-#ifdef CONFIG_TMPFS_POSIX_ACL
-int shmem_check_acl(struct inode *, int);
-int shmem_acl_init(struct inode *, struct inode *);
-
-extern struct xattr_handler shmem_xattr_acl_access_handler;
-extern struct xattr_handler shmem_xattr_acl_default_handler;
-
-extern struct generic_acl_operations shmem_acl_ops;
-
-#else
-static inline int shmem_acl_init(struct inode *inode, struct inode *dir)
-{
-	return 0;
-}
-#endif  /* CONFIG_TMPFS_POSIX_ACL */
-
 #endif
Index: linux-2.6/mm/shmem.c
===================================================================
--- linux-2.6.orig/mm/shmem.c	2009-09-26 11:53:37.843006812 -0300
+++ linux-2.6/mm/shmem.c	2009-09-26 11:54:15.177004046 -0300
@@ -42,6 +42,7 @@ static struct vfsmount *shm_mnt;
 
 #include <linux/xattr.h>
 #include <linux/exportfs.h>
+#include <linux/posix_acl.h>
 #include <linux/generic_acl.h>
 #include <linux/mman.h>
 #include <linux/string.h>
@@ -810,7 +811,7 @@ static int shmem_notify_change(struct de
 		error = inode_setattr(inode, attr);
 #ifdef CONFIG_TMPFS_POSIX_ACL
 	if (!error && (attr->ia_valid & ATTR_MODE))
-		error = generic_acl_chmod(inode, &shmem_acl_ops);
+		error = generic_acl_chmod(inode);
 #endif
 	if (page)
 		page_cache_release(page);
@@ -1817,11 +1818,13 @@ shmem_mknod(struct inode *dir, struct de
 				return error;
 			}
 		}
-		error = shmem_acl_init(inode, dir);
+#ifdef CONFIG_TMPFS_POSIX_ACL
+		error = generic_acl_init(inode, dir);
 		if (error) {
 			iput(inode);
 			return error;
 		}
+#endif
 		if (dir->i_mode & S_ISGID) {
 			inode->i_gid = dir->i_gid;
 			if (S_ISDIR(mode))
@@ -2068,8 +2071,8 @@ static struct xattr_handler shmem_xattr_
 };
 
 static struct xattr_handler *shmem_xattr_handlers[] = {
-	&shmem_xattr_acl_access_handler,
-	&shmem_xattr_acl_default_handler,
+	&generic_acl_access_handler,
+	&generic_acl_default_handler,
 	&shmem_xattr_security_handler,
 	NULL
 };
@@ -2448,7 +2451,7 @@ static const struct inode_operations shm
 	.getxattr	= generic_getxattr,
 	.listxattr	= generic_listxattr,
 	.removexattr	= generic_removexattr,
-	.check_acl	= shmem_check_acl,
+	.check_acl	= generic_check_acl,
 #endif
 
 };
@@ -2471,7 +2474,7 @@ static const struct inode_operations shm
 	.getxattr	= generic_getxattr,
 	.listxattr	= generic_listxattr,
 	.removexattr	= generic_removexattr,
-	.check_acl	= shmem_check_acl,
+	.check_acl	= generic_check_acl,
 #endif
 };
 
@@ -2482,7 +2485,7 @@ static const struct inode_operations shm
 	.getxattr	= generic_getxattr,
 	.listxattr	= generic_listxattr,
 	.removexattr	= generic_removexattr,
-	.check_acl	= shmem_check_acl,
+	.check_acl	= generic_check_acl,
 #endif
 };
 
Index: linux-2.6/mm/shmem_acl.c
===================================================================
--- linux-2.6.orig/mm/shmem_acl.c	2009-09-26 11:53:37.846007474 -0300
+++ /dev/null	1970-01-01 00:00:00.000000000 +0000
@@ -1,133 +0,0 @@
-/*
- * mm/shmem_acl.c
- *
- * (C) 2005 Andreas Gruenbacher <agruen@suse.de>
- *
- * This file is released under the GPL.
- */
-
-#include <linux/fs.h>
-#include <linux/shmem_fs.h>
-#include <linux/xattr.h>
-#include <linux/generic_acl.h>
-
-/**
- * shmem_get_acl  -   generic_acl_operations->getacl() operation
- */
-static struct posix_acl *
-shmem_get_acl(struct inode *inode, int type)
-{
-	struct posix_acl *acl = NULL;
-
-	spin_lock(&inode->i_lock);
-	switch(type) {
-		case ACL_TYPE_ACCESS:
-			acl = posix_acl_dup(inode->i_acl);
-			break;
-
-		case ACL_TYPE_DEFAULT:
-			acl = posix_acl_dup(inode->i_default_acl);
-			break;
-	}
-	spin_unlock(&inode->i_lock);
-
-	return acl;
-}
-
-/**
- * shmem_set_acl  -   generic_acl_operations->setacl() operation
- */
-static void
-shmem_set_acl(struct inode *inode, int type, struct posix_acl *acl)
-{
-	struct posix_acl *free = NULL;
-
-	spin_lock(&inode->i_lock);
-	switch(type) {
-		case ACL_TYPE_ACCESS:
-			free = inode->i_acl;
-			inode->i_acl = posix_acl_dup(acl);
-			break;
-
-		case ACL_TYPE_DEFAULT:
-			free = inode->i_default_acl;
-			inode->i_default_acl = posix_acl_dup(acl);
-			break;
-	}
-	spin_unlock(&inode->i_lock);
-	posix_acl_release(free);
-}
-
-struct generic_acl_operations shmem_acl_ops = {
-	.getacl = shmem_get_acl,
-	.setacl = shmem_set_acl,
-};
-
-static size_t
-shmem_xattr_list_acl(struct dentry *dentry, char *list, size_t list_size,
-		const char *name, size_t name_len, int type)
-{
-	return generic_acl_list(dentry->d_inode, &shmem_acl_ops,
-				type, list, list_size);
-}
-
-static int
-shmem_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer,
-		     size_t size, int type)
-{
-	if (strcmp(name, "") != 0)
-		return -EINVAL;
-	return generic_acl_get(dentry->d_inode, &shmem_acl_ops, type,
-			       buffer, size);
-}
-
-static int
-shmem_xattr_set_acl(struct dentry *dentry, const char *name, const void *value,
-		     size_t size, int flags, int type)
-{
-	if (strcmp(name, "") != 0)
-		return -EINVAL;
-	return generic_acl_set(dentry->d_inode, &shmem_acl_ops, type,
-			       value, size);
-}
-
-struct xattr_handler shmem_xattr_acl_access_handler = {
-	.prefix = POSIX_ACL_XATTR_ACCESS,
-	.flags	= ACL_TYPE_ACCESS,
-	.list	= shmem_xattr_list_acl,
-	.get	= shmem_xattr_get_acl,
-	.set	= shmem_xattr_set_acl,
-};
-
-struct xattr_handler shmem_xattr_acl_default_handler = {
-	.prefix = POSIX_ACL_XATTR_DEFAULT,
-	.flags	= ACL_TYPE_DEFAULT,
-	.list	= shmem_xattr_list_acl,
-	.get	= shmem_xattr_get_acl,
-	.set	= shmem_xattr_set_acl,
-};
-
-/**
- * shmem_acl_init  -  Inizialize the acl(s) of a new inode
- */
-int
-shmem_acl_init(struct inode *inode, struct inode *dir)
-{
-	return generic_acl_init(inode, dir, &shmem_acl_ops);
-}
-
-/**
- * shmem_check_acl  -  check_acl() callback for generic_permission()
- */
-int
-shmem_check_acl(struct inode *inode, int mask)
-{
-	struct posix_acl *acl = shmem_get_acl(inode, ACL_TYPE_ACCESS);
-
-	if (acl) {
-		int error = posix_acl_permission(inode, acl, mask);
-		posix_acl_release(acl);
-		return error;
-	}
-	return -EAGAIN;
-}
Index: linux-2.6/mm/Makefile
===================================================================
--- linux-2.6.orig/mm/Makefile	2009-09-25 16:57:56.079003962 -0300
+++ linux-2.6/mm/Makefile	2009-09-26 11:54:15.178003475 -0300
@@ -22,7 +22,6 @@ obj-$(CONFIG_HUGETLBFS)	+= hugetlb.o
 obj-$(CONFIG_NUMA) 	+= mempolicy.o
 obj-$(CONFIG_SPARSEMEM)	+= sparse.o
 obj-$(CONFIG_SPARSEMEM_VMEMMAP) += sparse-vmemmap.o
-obj-$(CONFIG_TMPFS_POSIX_ACL) += shmem_acl.o
 obj-$(CONFIG_SLOB) += slob.o
 obj-$(CONFIG_MMU_NOTIFIER) += mmu_notifier.o
 obj-$(CONFIG_KSM) += ksm.o