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-rw-r--r--fs/cramfs/inode.c1002
1 files changed, 1002 insertions, 0 deletions
diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c
new file mode 100644
index 000000000..6dae27d6f
--- /dev/null
+++ b/fs/cramfs/inode.c
@@ -0,0 +1,1002 @@
+/*
+ * Compressed rom filesystem for Linux.
+ *
+ * Copyright (C) 1999 Linus Torvalds.
+ *
+ * This file is released under the GPL.
+ */
+
+/*
+ * These are the VFS interfaces to the compressed rom filesystem.
+ * The actual compression is based on zlib, see the other files.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#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/fs_context.h>
+#include <linux/slab.h>
+#include <linux/vfs.h>
+#include <linux/mutex.h>
+#include <uapi/linux/cramfs_fs.h>
+#include <linux/uaccess.h>
+
+#include "internal.h"
+
+/*
+ * cramfs super-block data in memory
+ */
+struct cramfs_sb_info {
+ unsigned long magic;
+ unsigned long size;
+ 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)
+{
+ return sb->s_fs_info;
+}
+
+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);
+
+
+/* These macros may change in future, to provide better st_ino semantics. */
+#define OFFSET(x) ((x)->i_ino)
+
+static unsigned long cramino(const 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,
+ const struct cramfs_inode *cramfs_inode, unsigned int offset)
+{
+ struct inode *inode;
+ static struct timespec64 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;
+ 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;
+ inode->i_fop = &cramfs_directory_operations;
+ break;
+ case S_IFLNK:
+ inode->i_op = &page_symlink_inode_operations;
+ inode_nohighmem(inode);
+ 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;
+ i_uid_write(inode, cramfs_inode->uid);
+ i_gid_write(inode, 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. */
+
+ unlock_new_inode(inode);
+
+ 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_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)]. */
+#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_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;
+
+/*
+ * Populate our block cache and return a pointer to it.
+ */
+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 file_ra_state ra = {};
+ struct page *pages[BLKS_PER_BUF];
+ unsigned i, blocknr, buffer;
+ unsigned long devsize;
+ char *data;
+
+ if (!len)
+ return NULL;
+ blocknr = offset >> PAGE_SHIFT;
+ offset &= PAGE_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_SHIFT;
+ blk_offset += offset;
+ if (blk_offset > BUFFER_SIZE ||
+ blk_offset + len > BUFFER_SIZE)
+ continue;
+ return read_buffers[i] + blk_offset;
+ }
+
+ devsize = bdev_nr_bytes(sb->s_bdev) >> PAGE_SHIFT;
+
+ /* Ok, read in BLKS_PER_BUF pages completely first. */
+ file_ra_state_init(&ra, mapping);
+ page_cache_sync_readahead(mapping, &ra, NULL, blocknr, BLKS_PER_BUF);
+
+ for (i = 0; i < BLKS_PER_BUF; i++) {
+ struct page *page = NULL;
+
+ if (blocknr + i < devsize) {
+ page = read_mapping_page(mapping, blocknr + i, NULL);
+ /* synchronous error? */
+ if (IS_ERR(page))
+ page = NULL;
+ }
+ pages[i] = page;
+ }
+
+ 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_SIZE);
+ kunmap(page);
+ put_page(page);
+ } else
+ memset(data, 0, PAGE_SIZE);
+ data += PAGE_SIZE;
+ }
+ 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: %pD: last page is shared\n", file);
+ 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_read_folio().
+ */
+ int i;
+ vma->vm_flags |= VM_MIXEDMAP;
+ for (i = 0; i < pages && !ret; i++) {
+ vm_fault_t vmf;
+ unsigned long off = i * PAGE_SIZE;
+ pfn_t pfn = phys_to_pfn_t(address + off, PFN_DEV);
+ vmf = vmf_insert_mixed(vma, vma->vm_start + off, pfn);
+ if (vmf & VM_FAULT_ERROR)
+ ret = vm_fault_to_errno(vmf, 0);
+ }
+ }
+
+ if (!ret)
+ pr_debug("mapped %pD[%lu] at 0x%08lx (%u/%lu pages) "
+ "to vma 0x%08lx, page_prot 0x%llx\n", file,
+ pgoff, address, pages, vma_pages(vma), vma->vm_start,
+ (unsigned long long)pgprot_val(vma->vm_page_prot));
+ return ret;
+
+bailout:
+ pr_debug("%pD[%lu]: direct mmap impossible: %s\n",
+ file, 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 %pD ofs %#lx siz %lu at 0x%08lx\n",
+ file, 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);
+
+ if (IS_ENABLED(CONFIG_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);
+}
+
+static int cramfs_reconfigure(struct fs_context *fc)
+{
+ sync_filesystem(fc->root->d_sb);
+ fc->sb_flags |= SB_RDONLY;
+ return 0;
+}
+
+static int cramfs_read_super(struct super_block *sb, struct fs_context *fc,
+ struct cramfs_super *super)
+{
+ struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
+ unsigned long root_offset;
+ bool silent = fc->sb_flags & SB_SILENT;
+
+ /* We don't know the real size yet */
+ sbi->size = PAGE_SIZE;
+
+ /* Read the first block and get the superblock from it */
+ 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) {
+ /* check for wrong endianness */
+ if (super->magic == CRAMFS_MAGIC_WEND) {
+ if (!silent)
+ errorfc(fc, "wrong endianness");
+ return -EINVAL;
+ }
+
+ /* check at 512 byte offset */
+ mutex_lock(&read_mutex);
+ 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)
+ errorfc(fc, "wrong endianness");
+ else if (!silent)
+ errorfc(fc, "wrong magic");
+ return -EINVAL;
+ }
+ }
+
+ /* get feature flags first */
+ if (super->flags & ~CRAMFS_SUPPORTED_FLAGS) {
+ errorfc(fc, "unsupported filesystem features");
+ return -EINVAL;
+ }
+
+ /* Check that the root inode is in a sane state */
+ if (!S_ISDIR(super->root.mode)) {
+ errorfc(fc, "root is not a directory");
+ return -EINVAL;
+ }
+ /* correct strange, hard-coded permissions of mkcramfs */
+ 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;
+ } else {
+ sbi->size = 1<<28;
+ sbi->blocks = 0;
+ sbi->files = 0;
+ }
+ sbi->magic = super->magic;
+ sbi->flags = super->flags;
+ if (root_offset == 0)
+ infofc(fc, "empty filesystem");
+ else if (!(super->flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) &&
+ ((root_offset != sizeof(struct cramfs_super)) &&
+ (root_offset != 512 + sizeof(struct cramfs_super))))
+ {
+ errorfc(fc, "bad root offset %lu", root_offset);
+ 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 |= SB_RDONLY;
+ sb->s_time_min = 0;
+ sb->s_time_max = 0;
+ sb->s_op = &cramfs_ops;
+ root = get_cramfs_inode(sb, cramfs_root, 0);
+ if (IS_ERR(root))
+ return PTR_ERR(root);
+ sb->s_root = d_make_root(root);
+ if (!sb->s_root)
+ return -ENOMEM;
+ return 0;
+}
+
+static int cramfs_blkdev_fill_super(struct super_block *sb, struct fs_context *fc)
+{
+ 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, fc, &super);
+ if (err)
+ return err;
+ return cramfs_finalize_super(sb, &super.root);
+}
+
+static int cramfs_mtd_fill_super(struct super_block *sb, struct fs_context *fc)
+{
+ 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, fc, &super);
+ 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 = 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;
+ buf->f_blocks = CRAMFS_SB(sb)->blocks;
+ buf->f_bfree = 0;
+ buf->f_bavail = 0;
+ buf->f_files = CRAMFS_SB(sb)->files;
+ buf->f_ffree = 0;
+ buf->f_fsid = u64_to_fsid(id);
+ buf->f_namelen = CRAMFS_MAXPATHLEN;
+ return 0;
+}
+
+/*
+ * Read a cramfs directory entry.
+ */
+static int cramfs_readdir(struct file *file, struct dir_context *ctx)
+{
+ struct inode *inode = file_inode(file);
+ struct super_block *sb = inode->i_sb;
+ char *buf;
+ unsigned int offset;
+
+ /* Offset within the thing. */
+ if (ctx->pos >= inode->i_size)
+ return 0;
+ offset = ctx->pos;
+ /* Directory entries are always 4-byte aligned */
+ if (offset & 3)
+ return -EINVAL;
+
+ buf = kmalloc(CRAMFS_MAXPATHLEN, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ while (offset < inode->i_size) {
+ struct cramfs_inode *de;
+ unsigned long nextoffset;
+ char *name;
+ ino_t ino;
+ umode_t mode;
+ int namelen;
+
+ mutex_lock(&read_mutex);
+ de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN);
+ name = (char *)(de+1);
+
+ /*
+ * Namelengths on disk are shifted by two
+ * and the name padded out to 4-byte boundaries
+ * with zeroes.
+ */
+ namelen = de->namelen << 2;
+ memcpy(buf, name, namelen);
+ ino = cramino(de, OFFSET(inode) + offset);
+ mode = de->mode;
+ mutex_unlock(&read_mutex);
+ nextoffset = offset + sizeof(*de) + namelen;
+ for (;;) {
+ if (!namelen) {
+ kfree(buf);
+ return -EIO;
+ }
+ if (buf[namelen-1])
+ break;
+ namelen--;
+ }
+ if (!dir_emit(ctx, buf, namelen, ino, mode >> 12))
+ break;
+
+ ctx->pos = offset = nextoffset;
+ }
+ kfree(buf);
+ return 0;
+}
+
+/*
+ * Lookup and fill in the inode data..
+ */
+static struct dentry *cramfs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
+{
+ unsigned int offset = 0;
+ struct inode *inode = NULL;
+ int sorted;
+
+ mutex_lock(&read_mutex);
+ sorted = CRAMFS_SB(dir->i_sb)->flags & CRAMFS_FLAG_SORTED_DIRS;
+ while (offset < dir->i_size) {
+ struct cramfs_inode *de;
+ char *name;
+ int namelen, retval;
+ int dir_off = OFFSET(dir) + offset;
+
+ de = cramfs_read(dir->i_sb, dir_off, sizeof(*de)+CRAMFS_MAXPATHLEN);
+ name = (char *)(de+1);
+
+ /* Try to take advantage of sorted directories */
+ if (sorted && (dentry->d_name.name[0] < name[0]))
+ break;
+
+ namelen = de->namelen << 2;
+ offset += sizeof(*de) + namelen;
+
+ /* Quick check that the name is roughly the right length */
+ if (((dentry->d_name.len + 3) & ~3) != namelen)
+ continue;
+
+ for (;;) {
+ if (!namelen) {
+ inode = ERR_PTR(-EIO);
+ goto out;
+ }
+ if (name[namelen-1])
+ break;
+ namelen--;
+ }
+ if (namelen != dentry->d_name.len)
+ continue;
+ retval = memcmp(dentry->d_name.name, name, namelen);
+ if (retval > 0)
+ continue;
+ if (!retval) {
+ inode = get_cramfs_inode(dir->i_sb, de, dir_off);
+ break;
+ }
+ /* else (retval < 0) */
+ if (sorted)
+ break;
+ }
+out:
+ mutex_unlock(&read_mutex);
+ return d_splice_alias(inode, dentry);
+}
+
+static int cramfs_read_folio(struct file *file, struct folio *folio)
+{
+ struct page *page = &folio->page;
+ struct inode *inode = page->mapping->host;
+ u32 maxblock;
+ int bytes_filled;
+ void *pgdata;
+
+ maxblock = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ bytes_filled = 0;
+ pgdata = kmap(page);
+
+ if (page->index < maxblock) {
+ struct super_block *sb = inode->i_sb;
+ u32 blkptr_offset = OFFSET(inode) + page->index * 4;
+ u32 block_ptr, block_start, block_len;
+ bool uncompressed, direct;
+
+ mutex_lock(&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 (block_len == 0)
+ ; /* hole */
+ 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 {
+ bytes_filled = cramfs_uncompress_block(pgdata,
+ PAGE_SIZE,
+ 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);
+ flush_dcache_page(page);
+ kunmap(page);
+ SetPageUptodate(page);
+ unlock_page(page);
+ return 0;
+
+err:
+ kunmap(page);
+ ClearPageUptodate(page);
+ SetPageError(page);
+ unlock_page(page);
+ return 0;
+}
+
+static const struct address_space_operations cramfs_aops = {
+ .read_folio = cramfs_read_folio
+};
+
+/*
+ * Our operations:
+ */
+
+/*
+ * A directory can only readdir
+ */
+static const struct file_operations cramfs_directory_operations = {
+ .llseek = generic_file_llseek,
+ .read = generic_read_dir,
+ .iterate_shared = cramfs_readdir,
+};
+
+static const struct inode_operations cramfs_dir_inode_operations = {
+ .lookup = cramfs_lookup,
+};
+
+static const struct super_operations cramfs_ops = {
+ .statfs = cramfs_statfs,
+};
+
+static int cramfs_get_tree(struct fs_context *fc)
+{
+ int ret = -ENOPROTOOPT;
+
+ if (IS_ENABLED(CONFIG_CRAMFS_MTD)) {
+ ret = get_tree_mtd(fc, cramfs_mtd_fill_super);
+ if (!ret)
+ return 0;
+ }
+ if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV))
+ ret = get_tree_bdev(fc, cramfs_blkdev_fill_super);
+ return ret;
+}
+
+static const struct fs_context_operations cramfs_context_ops = {
+ .get_tree = cramfs_get_tree,
+ .reconfigure = cramfs_reconfigure,
+};
+
+/*
+ * Set up the filesystem mount context.
+ */
+static int cramfs_init_fs_context(struct fs_context *fc)
+{
+ fc->ops = &cramfs_context_ops;
+ return 0;
+}
+
+static struct file_system_type cramfs_fs_type = {
+ .owner = THIS_MODULE,
+ .name = "cramfs",
+ .init_fs_context = cramfs_init_fs_context,
+ .kill_sb = cramfs_kill_sb,
+ .fs_flags = FS_REQUIRES_DEV,
+};
+MODULE_ALIAS_FS("cramfs");
+
+static int __init init_cramfs_fs(void)
+{
+ int rv;
+
+ rv = cramfs_uncompress_init();
+ if (rv < 0)
+ return rv;
+ rv = register_filesystem(&cramfs_fs_type);
+ if (rv < 0)
+ cramfs_uncompress_exit();
+ return rv;
+}
+
+static void __exit exit_cramfs_fs(void)
+{
+ cramfs_uncompress_exit();
+ unregister_filesystem(&cramfs_fs_type);
+}
+
+module_init(init_cramfs_fs)
+module_exit(exit_cramfs_fs)
+MODULE_LICENSE("GPL");
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-04 09:54:31 +0000