2.6.22-rc6-mm1: BUG_ON() mm/memory.c, vm_insert_pfn(), filemap_xip.c, and spufs
From: Jared Hulbert
Date: Tue Jul 03 2007 - 21:10:04 EST
Recently there has been some discussion of the possiblity of reworking
some of filemap_xip.c to be pfn oriented. This would allow an XIP
fork of cramfs to use the filemap_xip framework. Today this is not
possible.
I've been trying out vm_insert_pfn() to start down that road. I used
spufs as a reference for how to use it. The include patch to cramfs
is my hack at it.
When I try to execute an XIP binary I get a BUG() on 2.6.22-rc6-mm1 at
mm/memory.c line 2334. The way I read this is says that spufs might
not work. I can't test it.
In spufs_mem_mmap() line 196 the vma is flagged as VM_PFNMAP:
vma->vm_flags |= VM_IO | VM_PFNMAP;
When you get a fault in a vma __do_fault() will get this vma and
BUG() on line 2334:
BUG_ON(vma->vm_flags & VM_PFNMAP);
What happened to the functionality of do_no_pfn()?
diff -r 74bad9e01817 fs/Kconfig
--- a/fs/Kconfig Thu Jun 28 13:49:43 2007 -0700
+++ b/fs/Kconfig Mon Jul 02 15:47:16 2007 -0700
@@ -65,8 +65,7 @@ config FS_XIP
config FS_XIP
# execute in place
bool
- depends on EXT2_FS_XIP
- default y
+ default n
config EXT3_FS
tristate "Ext3 journalling file system support"
@@ -1399,8 +1398,8 @@ endchoice
config CRAMFS
tristate "Compressed ROM file system support (cramfs)"
- depends on BLOCK
select ZLIB_INFLATE
+ select FS_XIP
help
Saying Y here includes support for CramFs (Compressed ROM File
System). CramFs is designed to be a simple, small, and compressed
diff -r 74bad9e01817 fs/cramfs/inode.c
--- a/fs/cramfs/inode.c Thu Jun 28 13:49:43 2007 -0700
+++ b/fs/cramfs/inode.c Tue Jul 03 17:45:42 2007 -0700
@@ -24,15 +24,21 @@
#include <linux/vfs.h>
#include <linux/mutex.h>
#include <asm/semaphore.h>
-
+#include <linux/vmalloc.h>
#include <asm/uaccess.h>
+static const struct file_operations cramfs_xip_fops;
static const struct super_operations cramfs_ops;
static const struct inode_operations cramfs_dir_inode_operations;
static const struct file_operations cramfs_directory_operations;
static const struct address_space_operations cramfs_aops;
+static const struct address_space_operations cramfs_xip_aops;
static DEFINE_MUTEX(read_mutex);
+
+static struct backing_dev_info cramfs_backing_dev_info = {
+ .ra_pages = 0, /* No readahead */
+};
/* These two macros may change in future, to provide better st_ino
@@ -77,19 +83,31 @@ static int cramfs_iget5_set(struct inode
/* Struct copy intentional */
inode->i_mtime = inode->i_atime = inode->i_ctime = zerotime;
inode->i_ino = CRAMINO(cramfs_inode);
+
+ if (CRAMFS_INODE_IS_XIP(inode))
+ inode->i_mapping->backing_dev_info = &cramfs_backing_dev_info;
+
/* 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;
+ if (CRAMFS_INODE_IS_XIP(inode)) {
+ inode->i_fop = &cramfs_xip_fops;
+ inode->i_data.a_ops = &cramfs_xip_aops;
+ } else {
+ 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;
+ if (CRAMFS_INODE_IS_XIP(inode))
+ inode->i_data.a_ops = &cramfs_xip_aops;
+ else
+ inode->i_data.a_ops = &cramfs_aops;
} else {
inode->i_size = 0;
inode->i_blocks = 0;
@@ -111,34 +129,6 @@ static struct inode *get_cramfs_inode(st
return inode;
}
-/*
- * We have our own block cache: don't fill up the buffer cache
- * with the rom-image, because the way the filesystem is set
- * up the accesses should be fairly regular and cached in the
- * page cache and dentry tree anyway..
- *
- * This also acts as a way to guarantee contiguous areas of up to
- * BLKS_PER_BUF*PAGE_CACHE_SIZE, so that the caller doesn't need to
- * worry about end-of-buffer issues even when decompressing a full
- * page cache.
- */
-#define READ_BUFFERS (2)
-/* NEXT_BUFFER(): Loop over [0..(READ_BUFFERS-1)]. */
-#define NEXT_BUFFER(_ix) ((_ix) ^ 1)
-
-/*
- * BLKS_PER_BUF_SHIFT should be at least 2 to allow for "compressed"
- * data that takes up more space than the original and with unlucky
- * alignment.
- */
-#define BLKS_PER_BUF_SHIFT (2)
-#define BLKS_PER_BUF (1 << BLKS_PER_BUF_SHIFT)
-#define BUFFER_SIZE (BLKS_PER_BUF*PAGE_CACHE_SIZE)
-
-static unsigned char read_buffers[READ_BUFFERS][BUFFER_SIZE];
-static unsigned buffer_blocknr[READ_BUFFERS];
-static struct super_block * buffer_dev[READ_BUFFERS];
-static int next_buffer;
/*
* Returns a pointer to a buffer containing at least LEN bytes of
@@ -146,78 +136,11 @@ static int next_buffer;
*/
static void *cramfs_read(struct super_block *sb, unsigned int offset,
unsigned int len)
{
- struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
- struct page *pages[BLKS_PER_BUF];
- unsigned i, blocknr, buffer, unread;
- unsigned long devsize;
- char *data;
+ struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
if (!len)
return NULL;
- blocknr = offset >> PAGE_CACHE_SHIFT;
- offset &= PAGE_CACHE_SIZE - 1;
-
- /* Check if an existing buffer already has the data.. */
- for (i = 0; i < READ_BUFFERS; i++) {
- unsigned int blk_offset;
-
- if (buffer_dev[i] != sb)
- continue;
- if (blocknr < buffer_blocknr[i])
- continue;
- blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_CACHE_SHIFT;
- blk_offset += offset;
- if (blk_offset + len > BUFFER_SIZE)
- continue;
- return read_buffers[i] + blk_offset;
- }
-
- devsize = mapping->host->i_size >> PAGE_CACHE_SHIFT;
-
- /* Ok, read in BLKS_PER_BUF pages completely first. */
- unread = 0;
- for (i = 0; i < BLKS_PER_BUF; i++) {
- struct page *page = NULL;
-
- if (blocknr + i < devsize) {
- page = read_mapping_page_async(mapping, blocknr + i,
- NULL);
- /* synchronous error? */
- if (IS_ERR(page))
- page = NULL;
- }
- pages[i] = page;
- }
-
- for (i = 0; i < BLKS_PER_BUF; i++) {
- struct page *page = pages[i];
- if (page) {
- wait_on_page_locked(page);
- if (!PageUptodate(page)) {
- /* asynchronous error */
- page_cache_release(page);
- pages[i] = NULL;
- }
- }
- }
-
- buffer = next_buffer;
- next_buffer = NEXT_BUFFER(buffer);
- buffer_blocknr[buffer] = blocknr;
- buffer_dev[buffer] = sb;
-
- data = read_buffers[buffer];
- for (i = 0; i < BLKS_PER_BUF; i++) {
- struct page *page = pages[i];
- if (page) {
- memcpy(data, kmap(page), PAGE_CACHE_SIZE);
- kunmap(page);
- page_cache_release(page);
- } else
- memset(data, 0, PAGE_CACHE_SIZE);
- data += PAGE_CACHE_SIZE;
- }
- return read_buffers[buffer] + offset;
+ return sbi->linear_virt_addr + offset;
}
static void cramfs_put_super(struct super_block *sb)
@@ -234,11 +157,12 @@ static int cramfs_remount(struct super_b
static int cramfs_fill_super(struct super_block *sb, void *data, int silent)
{
- int i;
struct cramfs_super super;
unsigned long root_offset;
struct cramfs_sb_info *sbi;
struct inode *root;
+ unsigned long phys_addr;
+ char *p;
sb->s_flags |= MS_RDONLY;
@@ -247,11 +171,36 @@ static int cramfs_fill_super(struct supe
return -ENOMEM;
sb->s_fs_info = sbi;
- /* Invalidate the read buffers on mount: think disk change.. */
- mutex_lock(&read_mutex);
- for (i = 0; i < READ_BUFFERS; i++)
- buffer_blocknr[i] = -1;
-
+ p = strstr(data, "physaddr=");
+ if (!p)
+ goto out_kfree;
+
+ phys_addr = simple_strtoul(p + 9, NULL, 0);
+ if (phys_addr & (PAGE_SIZE-1)) {
+ printk(KERN_ERR "cramfs: physical address 0x%lx for linear"
+ "cramfs isn't aligned to a page boundary\n",
+ phys_addr);
+ goto out_kfree;
+ }
+
+ if (phys_addr == 0) {
+ printk(KERN_ERR "cramfs: physical address for linear cramfs"
+ "image can't be 0\n");
+ goto out_kfree;
+ }
+
+ printk(KERN_INFO "cramfs: checking physical address 0x%lx for linear"
+ "cramfs image\n", phys_addr);
+
+ /* Map only one page for now. Will remap it when fs size is known. */
+ sbi->linear_virt_addr = ioremap(phys_addr, PAGE_SIZE);
+ if (!sbi->linear_virt_addr) {
+ printk(KERN_ERR "cramfs: ioremap of the linear cramfs image"
+ "failed\n");
+ goto out_kfree;
+ }
+
+ mutex_lock(&read_mutex);
/* Read the first block and get the superblock from it */
memcpy(&super, cramfs_read(sb, 0, sizeof(super)), sizeof(super));
mutex_unlock(&read_mutex);
@@ -265,20 +214,20 @@ static int cramfs_fill_super(struct supe
if (super.magic != CRAMFS_MAGIC) {
if (!silent)
printk(KERN_ERR "cramfs: wrong magic\n");
- goto out;
+ goto out_iounmap;
}
}
/* get feature flags first */
if (super.flags & ~CRAMFS_SUPPORTED_FLAGS) {
printk(KERN_ERR "cramfs: unsupported filesystem features\n");
- goto out;
+ goto out_iounmap;
}
/* Check that the root inode is in a sane state */
if (!S_ISDIR(super.root.mode)) {
printk(KERN_ERR "cramfs: root is not a directory\n");
- goto out;
+ goto out_iounmap;
}
root_offset = super.root.offset << 2;
if (super.flags & CRAMFS_FLAG_FSID_VERSION_2) {
@@ -299,21 +248,35 @@ static int cramfs_fill_super(struct supe
(root_offset != 512 + sizeof(struct cramfs_super))))
{
printk(KERN_ERR "cramfs: bad root offset %lu\n", root_offset);
- goto out;
+ goto out_iounmap;
}
/* Set it all up.. */
sb->s_op = &cramfs_ops;
root = get_cramfs_inode(sb, &super.root);
if (!root)
- goto out;
+ goto out_iounmap;
sb->s_root = d_alloc_root(root);
if (!sb->s_root) {
iput(root);
- goto out;
- }
- return 0;
-out:
+ goto out_iounmap;
+ }
+
+ /* Remap the whole filesystem now */
+ iounmap(sbi->linear_virt_addr);
+ sbi->linear_virt_addr = ioremap(phys_addr, sbi->size);
+ if (!sbi->linear_virt_addr) {
+ printk(KERN_ERR "cramfs: ioremap of the linear cramfs image"
+ " failed\n");
+ goto out_iounmap;
+ }
+ sbi->linear_phys_addr = phys_addr;
+
+ return 0;
+
+ out_iounmap:
+ iounmap(sbi->linear_virt_addr);
+ out_kfree:
kfree(sbi);
sb->s_fs_info = NULL;
return -EINVAL;
@@ -332,6 +295,61 @@ static int cramfs_statfs(struct dentry *
buf->f_ffree = 0;
buf->f_namelen = CRAMFS_MAXPATHLEN;
return 0;
+}
+
+static struct page *cramfs_mem_mmap_fault(struct vm_area_struct *vma,
+ struct fault_data *fdata)
+{
+ struct file *file = vma->vm_file;
+ struct address_space *mapping = file->f_mapping;
+ struct inode *inode = mapping->host;
+ struct super_block *sb = inode->i_sb;
+ struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
+ unsigned long pfn;
+ unsigned long offset;
+ unsigned long address;
+
+ address = PAGE_ALIGN(sbi->linear_phys_addr + OFFSET(inode));
+ offset = fdata->pgoff << PAGE_SHIFT;
+ pfn = (address + offset) >> PAGE_SHIFT;
+ printk(KERN_ERR "cramfs_mem_mmap_fault: address=0x%lx offset=0x%lx
pfn=0x%lx\n",fdata->address,offset,pfn);
+ vm_insert_pfn(vma, fdata->address, pfn);
+ fdata->type = VM_FAULT_MINOR;
+ return NULL;
+}
+
+static struct vm_operations_struct cramfs_mem_mmap_vmops = {
+ .fault = cramfs_mem_mmap_fault,
+};
+
+static int cramfs_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
+ return -EINVAL;
+
+ if (vma->vm_flags & VM_WRITE)
+ return generic_file_mmap(file, vma);
+
+ vma->vm_flags |= VM_IO | VM_PFNMAP;
+ vma->vm_ops = &cramfs_mem_mmap_vmops;
+ return 0;
+}
+
+struct page *cramfs_get_xip_page(struct address_space *mapping,
sector_t offset,
+ int create)
+{
+ unsigned long address;
+ unsigned long offs = offset;
+ struct inode *inode = mapping->host;
+ struct super_block *sb = inode->i_sb;
+ struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
+
+ address = PAGE_ALIGN((unsigned long)(sbi->linear_virt_addr
+ + OFFSET(inode)));
+ offs *= 512; /* FIXME -- This shouldn't be hard coded */
+ address += offs;
+
+ return virt_to_page(address);
}
/*
@@ -503,12 +521,22 @@ static int cramfs_readpage(struct file *
}
static const struct address_space_operations cramfs_aops = {
- .readpage = cramfs_readpage
+ .readpage = cramfs_readpage,
+};
+
+static const struct address_space_operations cramfs_xip_aops = {
+ .readpage = cramfs_readpage,
+ .get_xip_page = cramfs_get_xip_page,
};
/*
* Our operations:
*/
+
+static const struct file_operations cramfs_xip_fops = {
+ .read = xip_file_read,
+ .mmap = cramfs_mmap,
+};
/*
* A directory can only readdir
@@ -532,16 +560,14 @@ static int cramfs_get_sb(struct file_sys
static int cramfs_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data, struct vfsmount *mnt)
{
- return get_sb_bdev(fs_type, flags, dev_name, data, cramfs_fill_super,
- mnt);
+ return get_sb_nodev(fs_type, flags, data, cramfs_fill_super, mnt);
}
static struct file_system_type cramfs_fs_type = {
.owner = THIS_MODULE,
.name = "cramfs",
.get_sb = cramfs_get_sb,
- .kill_sb = kill_block_super,
- .fs_flags = FS_REQUIRES_DEV,
+ .kill_sb = kill_anon_super,
};
static int __init init_cramfs_fs(void)
diff -r 74bad9e01817 include/linux/cramfs_fs_sb.h
--- a/include/linux/cramfs_fs_sb.h Thu Jun 28 13:49:43 2007 -0700
+++ b/include/linux/cramfs_fs_sb.h Tue Jul 03 13:25:58 2007 -0700
@@ -10,6 +10,8 @@ struct cramfs_sb_info {
unsigned long blocks;
unsigned long files;
unsigned long flags;
+ void __iomem *linear_virt_addr;
+ unsigned long linear_phys_addr;
};
static inline struct cramfs_sb_info *CRAMFS_SB(struct super_block *sb)
@@ -17,4 +19,7 @@ static inline struct cramfs_sb_info *CRA
return sb->s_fs_info;
}
+#define CRAMFS_INODE_IS_XIP(x) \
+ ((x)->i_mode & S_ISVTX)
+
#endif
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/