summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
Diffstat
-rw-r--r--Documentation/filesystems/cramfs.txt42
-rw-r--r--MAINTAINERS4
-rw-r--r--fs/cramfs/Kconfig39
-rw-r--r--fs/cramfs/README31
-rw-r--r--fs/cramfs/inode.c511
-rw-r--r--include/uapi/linux/cramfs_fs.h26
6 files changed, 584 insertions, 69 deletions
diff --git a/Documentation/filesystems/cramfs.txt b/Documentation/filesystems/cramfs.txt
index 4006298f6707..8e19a53d648b 100644
--- a/Documentation/filesystems/cramfs.txt
+++ b/Documentation/filesystems/cramfs.txt
@@ -45,6 +45,48 @@ you can just change the #define in mkcramfs.c, so long as you don't
mind the filesystem becoming unreadable to future kernels.
+Memory Mapped cramfs image
+--------------------------
+
+The CRAMFS_MTD Kconfig option adds support for loading data directly from
+a physical linear memory range (usually non volatile memory like Flash)
+instead of going through the block device layer. This saves some memory
+since no intermediate buffering is necessary to hold the data before
+decompressing.
+
+And when data blocks are kept uncompressed and properly aligned, they will
+automatically be mapped directly into user space whenever possible providing
+eXecute-In-Place (XIP) from ROM of read-only segments. Data segments mapped
+read-write (hence they have to be copied to RAM) may still be compressed in
+the cramfs image in the same file along with non compressed read-only
+segments. Both MMU and no-MMU systems are supported. This is particularly
+handy for tiny embedded systems with very tight memory constraints.
+
+The location of the cramfs image in memory is system dependent. You must
+know the proper physical address where the cramfs image is located and
+configure an MTD device for it. Also, that MTD device must be supported
+by a map driver that implements the "point" method. Examples of such
+MTD drivers are cfi_cmdset_0001 (Intel/Sharp CFI flash) or physmap
+(Flash device in physical memory map). MTD partitions based on such devices
+are fine too. Then that device should be specified with the "mtd:" prefix
+as the mount device argument. For example, to mount the MTD device named
+"fs_partition" on the /mnt directory:
+
+$ mount -t cramfs mtd:fs_partition /mnt
+
+To boot a kernel with this as root filesystem, suffice to specify
+something like "root=mtd:fs_partition" on the kernel command line.
+
+
+Tools
+-----
+
+A version of mkcramfs that can take advantage of the latest capabilities
+described above can be found here:
+
+https://github.com/npitre/cramfs-tools
+
+
For /usr/share/magic
--------------------
diff --git a/MAINTAINERS b/MAINTAINERS
index e04d108055f0..ec3ec17c6c11 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3720,8 +3720,8 @@ F: drivers/cpuidle/*
F: include/linux/cpuidle.h
CRAMFS FILESYSTEM
-W: http://sourceforge.net/projects/cramfs/
-S: Orphan / Obsolete
+M: Nicolas Pitre <nico@linaro.org>
+S: Maintained
F: Documentation/filesystems/cramfs.txt
F: fs/cramfs/
diff --git a/fs/cramfs/Kconfig b/fs/cramfs/Kconfig
index 11b29d491b7c..f937082f3244 100644
--- a/fs/cramfs/Kconfig
+++ b/fs/cramfs/Kconfig
@@ -1,6 +1,5 @@
config CRAMFS
- tristate "Compressed ROM file system support (cramfs) (OBSOLETE)"
- depends on BLOCK
+ tristate "Compressed ROM file system support (cramfs)"
select ZLIB_INFLATE
help
Saying Y here includes support for CramFs (Compressed ROM File
@@ -16,7 +15,39 @@ config CRAMFS
cramfs. Note that the root file system (the one containing the
directory /) cannot be compiled as a module.
- This filesystem is obsoleted by SquashFS, which is much better
- in terms of performance and features.
+ This filesystem is limited in capabilities and performance on
+ purpose to remain small and low on RAM usage. It is most suitable
+ for small embedded systems. If you have ample RAM to spare, you may
+ consider a more capable compressed filesystem such as SquashFS
+ which is much better in terms of performance and features.
+
+ If unsure, say N.
+
+config CRAMFS_BLOCKDEV
+ bool "Support CramFs image over a regular block device" if EXPERT
+ depends on CRAMFS && BLOCK
+ default y
+ help
+ This option allows the CramFs driver to load data from a regular
+ block device such a disk partition or a ramdisk.
+
+config CRAMFS_MTD
+ bool "Support CramFs image directly mapped in physical memory"
+ depends on CRAMFS && MTD
+ default y if !CRAMFS_BLOCKDEV
+ help
+ This option allows the CramFs driver to load data directly from
+ a linear adressed memory range (usually non volatile memory
+ like flash) instead of going through the block device layer.
+ This saves some memory since no intermediate buffering is
+ necessary.
+
+ The location of the CramFs image is determined by a
+ MTD device capable of direct memory mapping e.g. from
+ the 'physmap' map driver or a resulting MTD partition.
+ For example, this would mount the cramfs image stored in
+ the MTD partition named "xip_fs" on the /mnt mountpoint:
+
+ mount -t cramfs mtd:xip_fs /mnt
If unsure, say N.
diff --git a/fs/cramfs/README b/fs/cramfs/README
index 9d4e7ea311f4..d71b27e0ff15 100644
--- a/fs/cramfs/README
+++ b/fs/cramfs/README
@@ -49,17 +49,46 @@ same as the start of the (i+1)'th <block> if there is one). The first
<block> immediately follows the last <block_pointer> for the file.
<block_pointer>s are each 32 bits long.
+When the CRAMFS_FLAG_EXT_BLOCK_POINTERS capability bit is set, each
+<block_pointer>'s top bits may contain special flags as follows:
+
+CRAMFS_BLK_FLAG_UNCOMPRESSED (bit 31):
+ The block data is not compressed and should be copied verbatim.
+
+CRAMFS_BLK_FLAG_DIRECT_PTR (bit 30):
+ The <block_pointer> stores the actual block start offset and not
+ its end, shifted right by 2 bits. The block must therefore be
+ aligned to a 4-byte boundary. The block size is either blksize
+ if CRAMFS_BLK_FLAG_UNCOMPRESSED is also specified, otherwise
+ the compressed data length is included in the first 2 bytes of
+ the block data. This is used to allow discontiguous data layout
+ and specific data block alignments e.g. for XIP applications.
+
+
The order of <file_data>'s is a depth-first descent of the directory
tree, i.e. the same order as `find -size +0 \( -type f -o -type l \)
-print'.
<block>: The i'th <block> is the output of zlib's compress function
-applied to the i'th blksize-sized chunk of the input data.
+applied to the i'th blksize-sized chunk of the input data if the
+corresponding CRAMFS_BLK_FLAG_UNCOMPRESSED <block_ptr> bit is not set,
+otherwise it is the input data directly.
(For the last <block> of the file, the input may of course be smaller.)
Each <block> may be a different size. (See <block_pointer> above.)
+
<block>s are merely byte-aligned, not generally u32-aligned.
+When CRAMFS_BLK_FLAG_DIRECT_PTR is specified then the corresponding
+<block> may be located anywhere and not necessarily contiguous with
+the previous/next blocks. In that case it is minimally u32-aligned.
+If CRAMFS_BLK_FLAG_UNCOMPRESSED is also specified then the size is always
+blksize except for the last block which is limited by the file length.
+If CRAMFS_BLK_FLAG_DIRECT_PTR is set and CRAMFS_BLK_FLAG_UNCOMPRESSED
+is not set then the first 2 bytes of the block contains the size of the
+remaining block data as this cannot be determined from the placement of
+logically adjacent blocks.
+
Holes
-----
diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c
index 7919967488cb..9a2ab419ba62 100644
--- a/fs/cramfs/inode.c
+++ b/fs/cramfs/inode.c
@@ -15,10 +15,15 @@
#include <linux/module.h>
#include <linux/fs.h>
+#include <linux/file.h>
#include <linux/pagemap.h>
+#include <linux/pfn_t.h>
+#include <linux/ramfs.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/blkdev.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/super.h>
#include <linux/slab.h>
#include <linux/vfs.h>
#include <linux/mutex.h>
@@ -36,6 +41,9 @@ struct cramfs_sb_info {
unsigned long blocks;
unsigned long files;
unsigned long flags;
+ void *linear_virt_addr;
+ resource_size_t linear_phys_addr;
+ size_t mtd_point_size;
};
static inline struct cramfs_sb_info *CRAMFS_SB(struct super_block *sb)
@@ -46,6 +54,7 @@ static inline struct cramfs_sb_info *CRAMFS_SB(struct super_block *sb)
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 file_operations cramfs_physmem_fops;
static const struct address_space_operations cramfs_aops;
static DEFINE_MUTEX(read_mutex);
@@ -93,6 +102,10 @@ static struct inode *get_cramfs_inode(struct super_block *sb,
case S_IFREG:
inode->i_fop = &generic_ro_fops;
inode->i_data.a_ops = &cramfs_aops;
+ if (IS_ENABLED(CONFIG_CRAMFS_MTD) &&
+ CRAMFS_SB(sb)->flags & CRAMFS_FLAG_EXT_BLOCK_POINTERS &&
+ CRAMFS_SB(sb)->linear_phys_addr)
+ inode->i_fop = &cramfs_physmem_fops;
break;
case S_IFDIR:
inode->i_op = &cramfs_dir_inode_operations;
@@ -140,6 +153,9 @@ static struct inode *get_cramfs_inode(struct super_block *sb,
* BLKS_PER_BUF*PAGE_SIZE, so that the caller doesn't need to
* worry about end-of-buffer issues even when decompressing a full
* page cache.
+ *
+ * Note: This is all optimized away at compile time when
+ * CONFIG_CRAMFS_BLOCKDEV=n.
*/
#define READ_BUFFERS (2)
/* NEXT_BUFFER(): Loop over [0..(READ_BUFFERS-1)]. */
@@ -160,10 +176,10 @@ static struct super_block *buffer_dev[READ_BUFFERS];
static int next_buffer;
/*
- * Returns a pointer to a buffer containing at least LEN bytes of
- * filesystem starting at byte offset OFFSET into the filesystem.
+ * Populate our block cache and return a pointer to it.
*/
-static void *cramfs_read(struct super_block *sb, unsigned int offset, unsigned int len)
+static void *cramfs_blkdev_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];
@@ -239,11 +255,250 @@ static void *cramfs_read(struct super_block *sb, unsigned int offset, unsigned i
return read_buffers[buffer] + offset;
}
+/*
+ * Return a pointer to the linearly addressed cramfs image in memory.
+ */
+static void *cramfs_direct_read(struct super_block *sb, unsigned int offset,
+ unsigned int len)
+{
+ struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
+
+ if (!len)
+ return NULL;
+ if (len > sbi->size || offset > sbi->size - len)
+ return page_address(ZERO_PAGE(0));
+ return sbi->linear_virt_addr + offset;
+}
+
+/*
+ * Returns a pointer to a buffer containing at least LEN bytes of
+ * filesystem starting at byte offset OFFSET into the filesystem.
+ */
+static void *cramfs_read(struct super_block *sb, unsigned int offset,
+ unsigned int len)
+{
+ struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
+
+ if (IS_ENABLED(CONFIG_CRAMFS_MTD) && sbi->linear_virt_addr)
+ return cramfs_direct_read(sb, offset, len);
+ else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV))
+ return cramfs_blkdev_read(sb, offset, len);
+ else
+ return NULL;
+}
+
+/*
+ * For a mapping to be possible, we need a range of uncompressed and
+ * contiguous blocks. Return the offset for the first block and number of
+ * valid blocks for which that is true, or zero otherwise.
+ */
+static u32 cramfs_get_block_range(struct inode *inode, u32 pgoff, u32 *pages)
+{
+ struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);
+ int i;
+ u32 *blockptrs, first_block_addr;
+
+ /*
+ * We can dereference memory directly here as this code may be
+ * reached only when there is a direct filesystem image mapping
+ * available in memory.
+ */
+ blockptrs = (u32 *)(sbi->linear_virt_addr + OFFSET(inode) + pgoff * 4);
+ first_block_addr = blockptrs[0] & ~CRAMFS_BLK_FLAGS;
+ i = 0;
+ do {
+ u32 block_off = i * (PAGE_SIZE >> CRAMFS_BLK_DIRECT_PTR_SHIFT);
+ u32 expect = (first_block_addr + block_off) |
+ CRAMFS_BLK_FLAG_DIRECT_PTR |
+ CRAMFS_BLK_FLAG_UNCOMPRESSED;
+ if (blockptrs[i] != expect) {
+ pr_debug("range: block %d/%d got %#x expects %#x\n",
+ pgoff+i, pgoff + *pages - 1,
+ blockptrs[i], expect);
+ if (i == 0)
+ return 0;
+ break;
+ }
+ } while (++i < *pages);
+
+ *pages = i;
+ return first_block_addr << CRAMFS_BLK_DIRECT_PTR_SHIFT;
+}
+
+#ifdef CONFIG_MMU
+
+/*
+ * Return true if the last page of a file in the filesystem image contains
+ * some other data that doesn't belong to that file. It is assumed that the
+ * last block is CRAMFS_BLK_FLAG_DIRECT_PTR | CRAMFS_BLK_FLAG_UNCOMPRESSED
+ * (verified by cramfs_get_block_range() and directly accessible in memory.
+ */
+static bool cramfs_last_page_is_shared(struct inode *inode)
+{
+ struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);
+ u32 partial, last_page, blockaddr, *blockptrs;
+ char *tail_data;
+
+ partial = offset_in_page(inode->i_size);
+ if (!partial)
+ return false;
+ last_page = inode->i_size >> PAGE_SHIFT;
+ blockptrs = (u32 *)(sbi->linear_virt_addr + OFFSET(inode));
+ blockaddr = blockptrs[last_page] & ~CRAMFS_BLK_FLAGS;
+ blockaddr <<= CRAMFS_BLK_DIRECT_PTR_SHIFT;
+ tail_data = sbi->linear_virt_addr + blockaddr + partial;
+ return memchr_inv(tail_data, 0, PAGE_SIZE - partial) ? true : false;
+}
+
+static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ struct inode *inode = file_inode(file);
+ struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);
+ unsigned int pages, max_pages, offset;
+ unsigned long address, pgoff = vma->vm_pgoff;
+ char *bailout_reason;
+ int ret;
+
+ ret = generic_file_readonly_mmap(file, vma);
+ if (ret)
+ return ret;
+
+ /*
+ * Now try to pre-populate ptes for this vma with a direct
+ * mapping avoiding memory allocation when possible.
+ */
+
+ /* Could COW work here? */
+ bailout_reason = "vma is writable";
+ if (vma->vm_flags & VM_WRITE)
+ goto bailout;
+
+ max_pages = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ bailout_reason = "beyond file limit";
+ if (pgoff >= max_pages)
+ goto bailout;
+ pages = min(vma_pages(vma), max_pages - pgoff);
+
+ offset = cramfs_get_block_range(inode, pgoff, &pages);
+ bailout_reason = "unsuitable block layout";
+ if (!offset)
+ goto bailout;
+ address = sbi->linear_phys_addr + offset;
+ bailout_reason = "data is not page aligned";
+ if (!PAGE_ALIGNED(address))
+ goto bailout;
+
+ /* Don't map the last page if it contains some other data */
+ if (pgoff + pages == max_pages && cramfs_last_page_is_shared(inode)) {
+ pr_debug("mmap: %s: last page is shared\n",
+ file_dentry(file)->d_name.name);
+ pages--;
+ }
+
+ if (!pages) {
+ bailout_reason = "no suitable block remaining";
+ goto bailout;
+ }
+
+ if (pages == vma_pages(vma)) {
+ /*
+ * The entire vma is mappable. remap_pfn_range() will
+ * make it distinguishable from a non-direct mapping
+ * in /proc/<pid>/maps by substituting the file offset
+ * with the actual physical address.
+ */
+ ret = remap_pfn_range(vma, vma->vm_start, address >> PAGE_SHIFT,
+ pages * PAGE_SIZE, vma->vm_page_prot);
+ } else {
+ /*
+ * Let's create a mixed map if we can't map it all.
+ * The normal paging machinery will take care of the
+ * unpopulated ptes via cramfs_readpage().
+ */
+ int i;
+ vma->vm_flags |= VM_MIXEDMAP;
+ for (i = 0; i < pages && !ret; i++) {
+ unsigned long off = i * PAGE_SIZE;
+ pfn_t pfn = phys_to_pfn_t(address + off, PFN_DEV);
+ ret = vm_insert_mixed(vma, vma->vm_start + off, pfn);
+ }
+ }
+
+ if (!ret)
+ pr_debug("mapped %s[%lu] at 0x%08lx (%u/%lu pages) "
+ "to vma 0x%08lx, page_prot 0x%llx\n",
+ file_dentry(file)->d_name.name, pgoff,
+ address, pages, vma_pages(vma), vma->vm_start,
+ (unsigned long long)pgprot_val(vma->vm_page_prot));
+ return ret;
+
+bailout:
+ pr_debug("%s[%lu]: direct mmap impossible: %s\n",
+ file_dentry(file)->d_name.name, pgoff, bailout_reason);
+ /* Didn't manage any direct map, but normal paging is still possible */
+ return 0;
+}
+
+#else /* CONFIG_MMU */
+
+static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ return vma->vm_flags & (VM_SHARED | VM_MAYSHARE) ? 0 : -ENOSYS;
+}
+
+static unsigned long cramfs_physmem_get_unmapped_area(struct file *file,
+ unsigned long addr, unsigned long len,
+ unsigned long pgoff, unsigned long flags)
+{
+ struct inode *inode = file_inode(file);
+ struct super_block *sb = inode->i_sb;
+ struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
+ unsigned int pages, block_pages, max_pages, offset;
+
+ pages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ max_pages = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ if (pgoff >= max_pages || pages > max_pages - pgoff)
+ return -EINVAL;
+ block_pages = pages;
+ offset = cramfs_get_block_range(inode, pgoff, &block_pages);
+ if (!offset || block_pages != pages)
+ return -ENOSYS;
+ addr = sbi->linear_phys_addr + offset;
+ pr_debug("get_unmapped for %s ofs %#lx siz %lu at 0x%08lx\n",
+ file_dentry(file)->d_name.name, pgoff*PAGE_SIZE, len, addr);
+ return addr;
+}
+
+static unsigned int cramfs_physmem_mmap_capabilities(struct file *file)
+{
+ return NOMMU_MAP_COPY | NOMMU_MAP_DIRECT |
+ NOMMU_MAP_READ | NOMMU_MAP_EXEC;
+}
+
+#endif /* CONFIG_MMU */
+
+static const struct file_operations cramfs_physmem_fops = {
+ .llseek = generic_file_llseek,
+ .read_iter = generic_file_read_iter,
+ .splice_read = generic_file_splice_read,
+ .mmap = cramfs_physmem_mmap,
+#ifndef CONFIG_MMU
+ .get_unmapped_area = cramfs_physmem_get_unmapped_area,
+ .mmap_capabilities = cramfs_physmem_mmap_capabilities,
+#endif
+};
+
static void cramfs_kill_sb(struct super_block *sb)
{
struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
- kill_block_super(sb);
+ if (IS_ENABLED(CCONFIG_CRAMFS_MTD) && sb->s_mtd) {
+ if (sbi && sbi->mtd_point_size)
+ mtd_unpoint(sb->s_mtd, 0, sbi->mtd_point_size);
+ kill_mtd_super(sb);
+ } else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV) && sb->s_bdev) {
+ kill_block_super(sb);
+ }
kfree(sbi);
}
@@ -254,34 +509,24 @@ static int cramfs_remount(struct super_block *sb, int *flags, char *data)
return 0;
}
-static int cramfs_fill_super(struct super_block *sb, void *data, int silent)
+static int cramfs_read_super(struct super_block *sb,
+ struct cramfs_super *super, int silent)
{
- int i;
- struct cramfs_super super;
+ struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
unsigned long root_offset;
- struct cramfs_sb_info *sbi;
- struct inode *root;
- sb->s_flags |= MS_RDONLY;
-
- sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
- if (!sbi)
- 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;
+ /* We don't know the real size yet */
+ sbi->size = PAGE_SIZE;
/* Read the first block and get the superblock from it */
- memcpy(&super, cramfs_read(sb, 0, sizeof(super)), sizeof(super));
+ mutex_lock(&read_mutex);
+ memcpy(super, cramfs_read(sb, 0, sizeof(*super)), sizeof(*super));
mutex_unlock(&read_mutex);
/* Do sanity checks on the superblock */
- if (super.magic != CRAMFS_MAGIC) {
+ if (super->magic != CRAMFS_MAGIC) {
/* check for wrong endianness */
- if (super.magic == CRAMFS_MAGIC_WEND) {
+ if (super->magic == CRAMFS_MAGIC_WEND) {
if (!silent)
pr_err("wrong endianness\n");
return -EINVAL;
@@ -289,10 +534,12 @@ static int cramfs_fill_super(struct super_block *sb, void *data, int silent)
/* check at 512 byte offset */
mutex_lock(&read_mutex);
- memcpy(&super, cramfs_read(sb, 512, sizeof(super)), sizeof(super));
+ memcpy(super,
+ cramfs_read(sb, 512, sizeof(*super)),
+ sizeof(*super));
mutex_unlock(&read_mutex);
- if (super.magic != CRAMFS_MAGIC) {
- if (super.magic == CRAMFS_MAGIC_WEND && !silent)
+ if (super->magic != CRAMFS_MAGIC) {
+ if (super->magic == CRAMFS_MAGIC_WEND && !silent)
pr_err("wrong endianness\n");
else if (!silent)
pr_err("wrong magic\n");
@@ -301,34 +548,34 @@ static int cramfs_fill_super(struct super_block *sb, void *data, int silent)
}
/* get feature flags first */
- if (super.flags & ~CRAMFS_SUPPORTED_FLAGS) {
+ if (super->flags & ~CRAMFS_SUPPORTED_FLAGS) {
pr_err("unsupported filesystem features\n");
return -EINVAL;
}
/* Check that the root inode is in a sane state */
- if (!S_ISDIR(super.root.mode)) {
+ if (!S_ISDIR(super->root.mode)) {
pr_err("root is not a directory\n");
return -EINVAL;
}
/* correct strange, hard-coded permissions of mkcramfs */
- super.root.mode |= (S_IRUSR | S_IXUSR | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH);
+ super->root.mode |= 0555;
- root_offset = super.root.offset << 2;
- if (super.flags & CRAMFS_FLAG_FSID_VERSION_2) {
- sbi->size = super.size;
- sbi->blocks = super.fsid.blocks;
- sbi->files = super.fsid.files;
+ root_offset = super->root.offset << 2;
+ if (super->flags & CRAMFS_FLAG_FSID_VERSION_2) {
+ sbi->size = super->size;
+ sbi->blocks = super->fsid.blocks;
+ sbi->files = super->fsid.files;
} else {
sbi->size = 1<<28;
sbi->blocks = 0;
sbi->files = 0;
}
- sbi->magic = super.magic;
- sbi->flags = super.flags;
+ sbi->magic = super->magic;
+ sbi->flags = super->flags;
if (root_offset == 0)
pr_info("empty filesystem");
- else if (!(super.flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) &&
+ else if (!(super->flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) &&
((root_offset != sizeof(struct cramfs_super)) &&
(root_offset != 512 + sizeof(struct cramfs_super))))
{
@@ -336,9 +583,18 @@ static int cramfs_fill_super(struct super_block *sb, void *data, int silent)
return -EINVAL;
}
+ return 0;
+}
+
+static int cramfs_finalize_super(struct super_block *sb,
+ struct cramfs_inode *cramfs_root)
+{
+ struct inode *root;
+
/* Set it all up.. */
+ sb->s_flags |= MS_RDONLY;
sb->s_op = &cramfs_ops;
- root = get_cramfs_inode(sb, &super.root, 0);
+ root = get_cramfs_inode(sb, cramfs_root, 0);
if (IS_ERR(root))
return PTR_ERR(root);
sb->s_root = d_make_root(root);
@@ -347,10 +603,79 @@ static int cramfs_fill_super(struct super_block *sb, void *data, int silent)
return 0;
}
+static int cramfs_blkdev_fill_super(struct super_block *sb, void *data,
+ int silent)
+{
+ struct cramfs_sb_info *sbi;
+ struct cramfs_super super;
+ int i, err;
+
+ sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
+ if (!sbi)
+ return -ENOMEM;
+ sb->s_fs_info = sbi;
+
+ /* Invalidate the read buffers on mount: think disk change.. */
+ for (i = 0; i < READ_BUFFERS; i++)
+ buffer_blocknr[i] = -1;
+
+ err = cramfs_read_super(sb, &super, silent);
+ if (err)
+ return err;
+ return cramfs_finalize_super(sb, &super.root);
+}
+
+static int cramfs_mtd_fill_super(struct super_block *sb, void *data,
+ int silent)
+{
+ struct cramfs_sb_info *sbi;
+ struct cramfs_super super;
+ int err;
+
+ sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
+ if (!sbi)
+ return -ENOMEM;
+ sb->s_fs_info = sbi;
+
+ /* Map only one page for now. Will remap it when fs size is known. */
+ err = mtd_point(sb->s_mtd, 0, PAGE_SIZE, &sbi->mtd_point_size,
+ &sbi->linear_virt_addr, &sbi->linear_phys_addr);
+ if (err || sbi->mtd_point_size != PAGE_SIZE) {
+ pr_err("unable to get direct memory access to mtd:%s\n",
+ sb->s_mtd->name);
+ return err ? : -ENODATA;
+ }
+
+ pr_info("checking physical address %pap for linear cramfs image\n",
+ &sbi->linear_phys_addr);
+ err = cramfs_read_super(sb, &super, silent);
+ if (err)
+ return err;
+
+ /* Remap the whole filesystem now */
+ pr_info("linear cramfs image on mtd:%s appears to be %lu KB in size\n",
+ sb->s_mtd->name, sbi->size/1024);
+ mtd_unpoint(sb->s_mtd, 0, PAGE_SIZE);
+ err = mtd_point(sb->s_mtd, 0, sbi->size, &sbi->mtd_point_size,
+ &sbi->linear_virt_addr, &sbi->linear_phys_addr);
+ if (err || sbi->mtd_point_size != sbi->size) {
+ pr_err("unable to get direct memory access to mtd:%s\n",
+ sb->s_mtd->name);
+ return err ? : -ENODATA;
+ }
+
+ return cramfs_finalize_super(sb, &super.root);
+}
+
static int cramfs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
struct super_block *sb = dentry->d_sb;
- u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
+ u64 id = 0;
+
+ if (sb->s_bdev)
+ id = huge_encode_dev(sb->s_bdev->bd_dev);
+ else if (sb->s_dev)
+ id = huge_encode_dev(sb->s_dev);
buf->f_type = CRAMFS_MAGIC;
buf->f_bsize = PAGE_SIZE;
@@ -502,34 +827,86 @@ static int cramfs_readpage(struct file *file, struct page *page)
if (page->index < maxblock) {
struct super_block *sb = inode->i_sb;
- u32 blkptr_offset = OFFSET(inode) + page->index*4;
- u32 start_offset, compr_len;
+ u32 blkptr_offset = OFFSET(inode) + page->index * 4;
+ u32 block_ptr, block_start, block_len;
+ bool uncompressed, direct;
- start_offset = OFFSET(inode) + maxblock*4;
mutex_lock(&read_mutex);
- if (page->index)
- start_offset = *(u32 *) cramfs_read(sb, blkptr_offset-4,
- 4);
- compr_len = (*(u32 *) cramfs_read(sb, blkptr_offset, 4) -
- start_offset);
- mutex_unlock(&read_mutex);
+ block_ptr = *(u32 *) cramfs_read(sb, blkptr_offset, 4);
+ uncompressed = (block_ptr & CRAMFS_BLK_FLAG_UNCOMPRESSED);
+ direct = (block_ptr & CRAMFS_BLK_FLAG_DIRECT_PTR);
+ block_ptr &= ~CRAMFS_BLK_FLAGS;
+
+ if (direct) {
+ /*
+ * The block pointer is an absolute start pointer,
+ * shifted by 2 bits. The size is included in the
+ * first 2 bytes of the data block when compressed,
+ * or PAGE_SIZE otherwise.
+ */
+ block_start = block_ptr << CRAMFS_BLK_DIRECT_PTR_SHIFT;
+ if (uncompressed) {
+ block_len = PAGE_SIZE;
+ /* if last block: cap to file length */
+ if (page->index == maxblock - 1)
+ block_len =
+ offset_in_page(inode->i_size);
+ } else {
+ block_len = *(u16 *)
+ cramfs_read(sb, block_start, 2);
+ block_start += 2;
+ }
+ } else {
+ /*
+ * The block pointer indicates one past the end of
+ * the current block (start of next block). If this
+ * is the first block then it starts where the block
+ * pointer table ends, otherwise its start comes
+ * from the previous block's pointer.
+ */
+ block_start = OFFSET(inode) + maxblock * 4;
+ if (page->index)
+ block_start = *(u32 *)
+ cramfs_read(sb, blkptr_offset - 4, 4);
+ /* Beware... previous ptr might be a direct ptr */
+ if (unlikely(block_start & CRAMFS_BLK_FLAG_DIRECT_PTR)) {
+ /* See comments on earlier code. */
+ u32 prev_start = block_start;
+ block_start = prev_start & ~CRAMFS_BLK_FLAGS;
+ block_start <<= CRAMFS_BLK_DIRECT_PTR_SHIFT;
+ if (prev_start & CRAMFS_BLK_FLAG_UNCOMPRESSED) {
+ block_start += PAGE_SIZE;
+ } else {
+ block_len = *(u16 *)
+ cramfs_read(sb, block_start, 2);
+ block_start += 2 + block_len;
+ }
+ }
+ block_start &= ~CRAMFS_BLK_FLAGS;
+ block_len = block_ptr - block_start;
+ }
- if (compr_len == 0)
+ if (block_len == 0)
; /* hole */
- else if (unlikely(compr_len > (PAGE_SIZE << 1))) {
- pr_err("bad compressed blocksize %u\n",
- compr_len);
+ else if (unlikely(block_len > 2*PAGE_SIZE ||
+ (uncompressed && block_len > PAGE_SIZE))) {
+ mutex_unlock(&read_mutex);
+ pr_err("bad data blocksize %u\n", block_len);
goto err;
+ } else if (uncompressed) {
+ memcpy(pgdata,
+ cramfs_read(sb, block_start, block_len),
+ block_len);
+ bytes_filled = block_len;
} else {
- mutex_lock(&read_mutex);
bytes_filled = cramfs_uncompress_block(pgdata,
PAGE_SIZE,
- cramfs_read(sb, start_offset, compr_len),
- compr_len);
- mutex_unlock(&read_mutex);
- if (unlikely(bytes_filled < 0))
- goto err;
+ cramfs_read(sb, block_start, block_len),
+ block_len);
}
+ mutex_unlock(&read_mutex);
+ if (unlikely(bytes_filled < 0))
+ goto err;
}
memset(pgdata + bytes_filled, 0, PAGE_SIZE - bytes_filled);
@@ -573,10 +950,22 @@ static const struct super_operations cramfs_ops = {
.statfs = cramfs_statfs,
};
-static struct dentry *cramfs_mount(struct file_system_type *fs_type,
- int flags, const char *dev_name, void *data)
+static struct dentry *cramfs_mount(struct file_system_type *fs_type, int flags,
+ const char *dev_name, void *data)
{
- return mount_bdev(fs_type, flags, dev_name, data, cramfs_fill_super);
+ struct dentry *ret = ERR_PTR(-ENOPROTOOPT);
+
+ if (IS_ENABLED(CONFIG_CRAMFS_MTD)) {
+ ret = mount_mtd(fs_type, flags, dev_name, data,
+ cramfs_mtd_fill_super);
+ if (!IS_ERR(ret))
+ return ret;
+ }
+ if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV)) {
+ ret = mount_bdev(fs_type, flags, dev_name, data,
+ cramfs_blkdev_fill_super);
+ }
+ return ret;
}
static struct file_system_type cramfs_fs_type = {
diff --git a/include/uapi/linux/cramfs_fs.h b/include/uapi/linux/cramfs_fs.h
index 5519504199e6..6713669aa2ed 100644
--- a/include/uapi/linux/cramfs_fs.h
+++ b/include/uapi/linux/cramfs_fs.h
@@ -74,6 +74,7 @@ struct cramfs_super {
#define CRAMFS_FLAG_HOLES 0x00000100 /* support for holes */
#define CRAMFS_FLAG_WRONG_SIGNATURE 0x00000200 /* reserved */
#define CRAMFS_FLAG_SHIFTED_ROOT_OFFSET 0x00000400 /* shifted root fs */
+#define CRAMFS_FLAG_EXT_BLOCK_POINTERS 0x00000800 /* block pointer extensions */
/*
* Valid values in super.flags. Currently we refuse to mount
@@ -83,7 +84,30 @@ struct cramfs_super {
#define CRAMFS_SUPPORTED_FLAGS ( 0x000000ff \
| CRAMFS_FLAG_HOLES \
| CRAMFS_FLAG_WRONG_SIGNATURE \
- | CRAMFS_FLAG_SHIFTED_ROOT_OFFSET )
+ | CRAMFS_FLAG_SHIFTED_ROOT_OFFSET \
+ | CRAMFS_FLAG_EXT_BLOCK_POINTERS )
+/*
+ * Block pointer flags
+ *
+ * The maximum block offset that needs to be represented is roughly:
+ *
+ * (1 << CRAMFS_OFFSET_WIDTH) * 4 +
+ * (1 << CRAMFS_SIZE_WIDTH) / PAGE_SIZE * (4 + PAGE_SIZE)
+ * = 0x11004000
+ *
+ * That leaves room for 3 flag bits in the block pointer table.
+ */
+#define CRAMFS_BLK_FLAG_UNCOMPRESSED (1 << 31)
+#define CRAMFS_BLK_FLAG_DIRECT_PTR (1 << 30)
+
+#define CRAMFS_BLK_FLAGS ( CRAMFS_BLK_FLAG_UNCOMPRESSED \
+ | CRAMFS_BLK_FLAG_DIRECT_PTR )
+
+/*
+ * Direct blocks are at least 4-byte aligned.
+ * Pointers to direct blocks are shifted down by 2 bits.
+ */
+#define CRAMFS_BLK_DIRECT_PTR_SHIFT 2
#endif /* _UAPI__CRAMFS_H */
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-20 18:10:59 +0000