cramfs: generate unique inode number for better inode cache usage

Generate a unique inode numbers for any entries in the cram file system. For files which did not contain data's (device nodes, fifos and sockets) the offset of the directory entry inside the cramfs plus 1 will be used as inode number. The + 1 for the inode will it make possible to distinguish between a file which contains no data and files which has data, the later one has a inode value where the lower two bits are always 0. It also reimplements the behavior to set the size and the number of block to 0 for special file, which is the right value for empty files, devices, fifos and sockets As a little benefit it will be also more compatible which older mkcramfs, because it will never use the cramfs_inode->offset for creating a inode number for special files. [akpm@linux-foundation.org: trivial comment fix] [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Stefani Seibold <stefani@seibold.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

cramfs: generate unique inode number for better inode cache usage
Generate a unique inode numbers for any entries in the cram file system. For files which did not contain data's (device nodes, fifos and sockets) the offset of the directory entry inside the cramfs plus 1 will be used as inode number. The + 1 for the inode will it make possible to distinguish between a file which contains no data and files which has data, the later one has a inode value where the lower two bits are always 0. It also reimplements the behavior to set the size and the number of block to 0 for special file, which is the right value for empty files, devices, fifos and sockets As a little benefit it will be also more compatible which older mkcramfs, because it will never use the cramfs_inode->offset for creating a inode number for special files. [akpm@linux-foundation.org: trivial comment fix] [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Stefani Seibold <stefani@seibold.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Stefani Seibold · Linus Torvalds
1 parent beeae05138
Showing 1 changed file with 69 additions and 41 deletions Side-by-side Diff
fs/cramfs/inode.c
@@ -34,57 +34,81 @@
 static DEFINE_MUTEX(read_mutex);
  
  
-/* These two macros may change in future, to provide better st_ino
-   semantics. */
-#define CRAMINO(x)	(((x)->offset && (x)->size)?(x)->offset<<2:1)
+/* These macros may change in future, to provide better st_ino semantics. */
 #define OFFSET(x)	((x)->i_ino)
  
-static void setup_inode(struct inode *inode, struct cramfs_inode * cramfs_inode)
+static unsigned long cramino(struct cramfs_inode *cino, unsigned int offset)
 {
+	if (!cino->offset)
+		return offset + 1;
+	if (!cino->size)
+		return offset + 1;
+
+	/*
+	 * The file mode test fixes buggy mkcramfs implementations where
+	 * cramfs_inode->offset is set to a non zero value for entries
+	 * which did not contain data, like devices node and fifos.
+	 */
+	switch (cino->mode & S_IFMT) {
+	case S_IFREG:
+	case S_IFDIR:
+	case S_IFLNK:
+		return cino->offset << 2;
+	default:
+		break;
+	}
+	return offset + 1;
+}
+
+static struct inode *get_cramfs_inode(struct super_block *sb,
+	struct cramfs_inode *cramfs_inode, unsigned int offset)
+{
+	struct inode *inode;
 	static struct timespec zerotime;
+
+	inode = iget_locked(sb, cramino(cramfs_inode, offset));
+	if (!inode)
+		return ERR_PTR(-ENOMEM);
+	if (!(inode->i_state & I_NEW))
+		return inode;
+
+	switch (cramfs_inode->mode & S_IFMT) {
+	case S_IFREG:
+		inode->i_fop = &generic_ro_fops;
+		inode->i_data.a_ops = &cramfs_aops;
+		break;
+	case S_IFDIR:
+		inode->i_op = &cramfs_dir_inode_operations;
+		inode->i_fop = &cramfs_directory_operations;
+		break;
+	case S_IFLNK:
+		inode->i_op = &page_symlink_inode_operations;
+		inode->i_data.a_ops = &cramfs_aops;
+		break;
+	default:
+		init_special_inode(inode, cramfs_inode->mode,
+				old_decode_dev(cramfs_inode->size));
+	}
+
 	inode->i_mode = cramfs_inode->mode;
 	inode->i_uid = cramfs_inode->uid;
-	inode->i_size = cramfs_inode->size;
-	inode->i_blocks = (cramfs_inode->size - 1) / 512 + 1;
 	inode->i_gid = cramfs_inode->gid;
+
+	/* if the lower 2 bits are zero, the inode contains data */
+	if (!(inode->i_ino & 3)) {
+		inode->i_size = cramfs_inode->size;
+		inode->i_blocks = (cramfs_inode->size - 1) / 512 + 1;
+	}
+
 	/* Struct copy intentional */
 	inode->i_mtime = inode->i_atime = inode->i_ctime = zerotime;
 	/* inode->i_nlink is left 1 - arguably wrong for directories,
 	   but it's the best we can do without reading the directory
 	   contents.  1 yields the right result in GNU find, even
 	   without -noleaf option. */
-	if (S_ISREG(inode->i_mode)) {
-		inode->i_fop = &generic_ro_fops;
-		inode->i_data.a_ops = &cramfs_aops;
-	} else if (S_ISDIR(inode->i_mode)) {
-		inode->i_op = &cramfs_dir_inode_operations;
-		inode->i_fop = &cramfs_directory_operations;
-	} else if (S_ISLNK(inode->i_mode)) {
-		inode->i_op = &page_symlink_inode_operations;
-		inode->i_data.a_ops = &cramfs_aops;
-	} else {
-		init_special_inode(inode, inode->i_mode,
-			old_decode_dev(cramfs_inode->size));
-	}
-}
  
-static struct inode *get_cramfs_inode(struct super_block *sb,
-				struct cramfs_inode * cramfs_inode)
-{
-	struct inode *inode;
-	if (CRAMINO(cramfs_inode) == 1) {
-		inode = new_inode(sb);
-		if (inode) {
-			inode->i_ino = 1;
-			setup_inode(inode, cramfs_inode);
-		}
-	} else {
-		inode = iget_locked(sb, CRAMINO(cramfs_inode));
-		if (inode && (inode->i_state & I_NEW)) {
-			setup_inode(inode, cramfs_inode);
-			unlock_new_inode(inode);
-		}
-	}
+	unlock_new_inode(inode);
+
 	return inode;
 }
  
@@ -265,6 +289,9 @@
 		printk(KERN_ERR "cramfs: root is not a directory\n");
 		goto out;
 	}
+	/* correct strange, hard-coded permissions of mkcramfs */
+	super.root.mode |= (S_IRUSR | S_IXUSR | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH);
+
 	root_offset = super.root.offset << 2;
 	if (super.flags & CRAMFS_FLAG_FSID_VERSION_2) {
 		sbi->size=super.size;
@@ -289,7 +316,7 @@
  
 	/* Set it all up.. */
 	sb->s_op = &cramfs_ops;
-	root = get_cramfs_inode(sb, &super.root);
+	root = get_cramfs_inode(sb, &super.root, 0);
 	if (!root)
 		goto out;
 	sb->s_root = d_alloc_root(root);
@@ -365,7 +392,7 @@
 		 */
 		namelen = de->namelen << 2;
 		memcpy(buf, name, namelen);
-		ino = CRAMINO(de);
+		ino = cramino(de, OFFSET(inode) + offset);
 		mode = de->mode;
 		mutex_unlock(&read_mutex);
 		nextoffset = offset + sizeof(*de) + namelen;
  
@@ -404,8 +431,9 @@
 		struct cramfs_inode *de;
 		char *name;
 		int namelen, retval;
+		int dir_off = OFFSET(dir) + offset;
  
-		de = cramfs_read(dir->i_sb, OFFSET(dir) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN);
+		de = cramfs_read(dir->i_sb, dir_off, sizeof(*de)+CRAMFS_MAXPATHLEN);
 		name = (char *)(de+1);
  
 		/* Try to take advantage of sorted directories */
@@ -436,7 +464,7 @@
 		if (!retval) {
 			struct cramfs_inode entry = *de;
 			mutex_unlock(&read_mutex);
-			d_add(dentry, get_cramfs_inode(dir->i_sb, &entry));
+			d_add(dentry, get_cramfs_inode(dir->i_sb, &entry, dir_off));
 			return NULL;
 		}
 		/* else (retval < 0) */
...	...	@@ -34,57 +34,81 @@
34	34	static DEFINE_MUTEX(read_mutex);
35	35
36	36
37		-/* These two macros may change in future, to provide better st_ino
38		- semantics. */
39		-#define CRAMINO(x) (((x)->offset && (x)->size)?(x)->offset<<2:1)
	37	+/* These macros may change in future, to provide better st_ino semantics. */
40	38	#define OFFSET(x) ((x)->i_ino)
41	39
42		-static void setup_inode(struct inode inode, struct cramfs_inode cramfs_inode)
	40	+static unsigned long cramino(struct cramfs_inode *cino, unsigned int offset)
43	41	{
	42	+ if (!cino->offset)
	43	+ return offset + 1;
	44	+ if (!cino->size)
	45	+ return offset + 1;
	46	+
	47	+ /*
	48	+ * The file mode test fixes buggy mkcramfs implementations where
	49	+ * cramfs_inode->offset is set to a non zero value for entries
	50	+ * which did not contain data, like devices node and fifos.
	51	+ */
	52	+ switch (cino->mode & S_IFMT) {
	53	+ case S_IFREG:
	54	+ case S_IFDIR:
	55	+ case S_IFLNK:
	56	+ return cino->offset << 2;
	57	+ default:
	58	+ break;
	59	+ }
	60	+ return offset + 1;
	61	+}
	62	+
	63	+static struct inode get_cramfs_inode(struct super_block sb,
	64	+ struct cramfs_inode *cramfs_inode, unsigned int offset)
	65	+{
	66	+ struct inode *inode;
44	67	static struct timespec zerotime;
	68	+
	69	+ inode = iget_locked(sb, cramino(cramfs_inode, offset));
	70	+ if (!inode)
	71	+ return ERR_PTR(-ENOMEM);
	72	+ if (!(inode->i_state & I_NEW))
	73	+ return inode;
	74	+
	75	+ switch (cramfs_inode->mode & S_IFMT) {
	76	+ case S_IFREG:
	77	+ inode->i_fop = &generic_ro_fops;
	78	+ inode->i_data.a_ops = &cramfs_aops;
	79	+ break;
	80	+ case S_IFDIR:
	81	+ inode->i_op = &cramfs_dir_inode_operations;
	82	+ inode->i_fop = &cramfs_directory_operations;
	83	+ break;
	84	+ case S_IFLNK:
	85	+ inode->i_op = &page_symlink_inode_operations;
	86	+ inode->i_data.a_ops = &cramfs_aops;
	87	+ break;
	88	+ default:
	89	+ init_special_inode(inode, cramfs_inode->mode,
	90	+ old_decode_dev(cramfs_inode->size));
	91	+ }
	92	+
45	93	inode->i_mode = cramfs_inode->mode;
46	94	inode->i_uid = cramfs_inode->uid;
47		- inode->i_size = cramfs_inode->size;
48		- inode->i_blocks = (cramfs_inode->size - 1) / 512 + 1;
49	95	inode->i_gid = cramfs_inode->gid;
	96	+
	97	+ /* if the lower 2 bits are zero, the inode contains data */
	98	+ if (!(inode->i_ino & 3)) {
	99	+ inode->i_size = cramfs_inode->size;
	100	+ inode->i_blocks = (cramfs_inode->size - 1) / 512 + 1;
	101	+ }
	102	+
50	103	/* Struct copy intentional */
51	104	inode->i_mtime = inode->i_atime = inode->i_ctime = zerotime;
52	105	/* inode->i_nlink is left 1 - arguably wrong for directories,
53	106	but it's the best we can do without reading the directory
54	107	contents. 1 yields the right result in GNU find, even
55	108	without -noleaf option. */
56		- if (S_ISREG(inode->i_mode)) {
57		- inode->i_fop = &generic_ro_fops;
58		- inode->i_data.a_ops = &cramfs_aops;
59		- } else if (S_ISDIR(inode->i_mode)) {
60		- inode->i_op = &cramfs_dir_inode_operations;
61		- inode->i_fop = &cramfs_directory_operations;
62		- } else if (S_ISLNK(inode->i_mode)) {
63		- inode->i_op = &page_symlink_inode_operations;
64		- inode->i_data.a_ops = &cramfs_aops;
65		- } else {
66		- init_special_inode(inode, inode->i_mode,
67		- old_decode_dev(cramfs_inode->size));
68		- }
69		-}
70	109
71		-static struct inode get_cramfs_inode(struct super_block sb,
72		- struct cramfs_inode * cramfs_inode)
73		-{
74		- struct inode *inode;
75		- if (CRAMINO(cramfs_inode) == 1) {
76		- inode = new_inode(sb);
77		- if (inode) {
78		- inode->i_ino = 1;
79		- setup_inode(inode, cramfs_inode);
80		- }
81		- } else {
82		- inode = iget_locked(sb, CRAMINO(cramfs_inode));
83		- if (inode && (inode->i_state & I_NEW)) {
84		- setup_inode(inode, cramfs_inode);
85		- unlock_new_inode(inode);
86		- }
87		- }
	110	+ unlock_new_inode(inode);
	111	+
88	112	return inode;
89	113	}
90	114
...	...	@@ -265,6 +289,9 @@
265	289	printk(KERN_ERR "cramfs: root is not a directory\n");
266	290	goto out;
267	291	}
	292	+ /* correct strange, hard-coded permissions of mkcramfs */
	293	+ super.root.mode \|= (S_IRUSR \| S_IXUSR \| S_IRGRP \| S_IXGRP \| S_IROTH \| S_IXOTH);
	294	+
268	295	root_offset = super.root.offset << 2;
269	296	if (super.flags & CRAMFS_FLAG_FSID_VERSION_2) {
270	297	sbi->size=super.size;
...	...	@@ -289,7 +316,7 @@
289	316
290	317	/* Set it all up.. */
291	318	sb->s_op = &cramfs_ops;
292		- root = get_cramfs_inode(sb, &super.root);
	319	+ root = get_cramfs_inode(sb, &super.root, 0);
293	320	if (!root)
294	321	goto out;
295	322	sb->s_root = d_alloc_root(root);
...	...	@@ -365,7 +392,7 @@
365	392	*/
366	393	namelen = de->namelen << 2;
367	394	memcpy(buf, name, namelen);
368		- ino = CRAMINO(de);
	395	+ ino = cramino(de, OFFSET(inode) + offset);
369	396	mode = de->mode;
370	397	mutex_unlock(&read_mutex);
371	398	nextoffset = offset + sizeof(*de) + namelen;
372	399
...	...	@@ -404,8 +431,9 @@
404	431	struct cramfs_inode *de;
405	432	char *name;
406	433	int namelen, retval;
	434	+ int dir_off = OFFSET(dir) + offset;
407	435
408		- de = cramfs_read(dir->i_sb, OFFSET(dir) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN);
	436	+ de = cramfs_read(dir->i_sb, dir_off, sizeof(*de)+CRAMFS_MAXPATHLEN);
409	437	name = (char *)(de+1);
410	438
411	439	/* Try to take advantage of sorted directories */
...	...	@@ -436,7 +464,7 @@
436	464	if (!retval) {
437	465	struct cramfs_inode entry = *de;
438	466	mutex_unlock(&read_mutex);
439		- d_add(dentry, get_cramfs_inode(dir->i_sb, &entry));
	467	+ d_add(dentry, get_cramfs_inode(dir->i_sb, &entry, dir_off));
440	468	return NULL;
441	469	}
442	470	/* else (retval < 0) */