diff options
| -rw-r--r-- | Documentation/filesystems/cramfs.txt | 42 | ||||
| -rw-r--r-- | MAINTAINERS | 4 | ||||
| -rw-r--r-- | fs/cramfs/Kconfig | 39 | ||||
| -rw-r--r-- | fs/cramfs/README | 31 | ||||
| -rw-r--r-- | fs/cramfs/inode.c | 511 | ||||
| -rw-r--r-- | include/uapi/linux/cramfs_fs.h | 26 |
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 */ |