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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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1013 lines
26 KiB
C
1013 lines
26 KiB
C
/*
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* Compressed rom filesystem for Linux.
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*
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* Copyright (C) 1999 Linus Torvalds.
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*
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* This file is released under the GPL.
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*/
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/*
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* These are the VFS interfaces to the compressed rom filesystem.
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* The actual compression is based on zlib, see the other files.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/fs.h>
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#include <linux/file.h>
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#include <linux/pagemap.h>
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#include <linux/pfn_t.h>
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#include <linux/ramfs.h>
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#include <linux/init.h>
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#include <linux/string.h>
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#include <linux/blkdev.h>
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#include <linux/mtd/mtd.h>
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#include <linux/mtd/super.h>
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#include <linux/fs_context.h>
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#include <linux/slab.h>
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#include <linux/vfs.h>
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#include <linux/mutex.h>
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#include <uapi/linux/cramfs_fs.h>
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#include <linux/uaccess.h>
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#include "internal.h"
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/*
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* cramfs super-block data in memory
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*/
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struct cramfs_sb_info {
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unsigned long magic;
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unsigned long size;
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unsigned long blocks;
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unsigned long files;
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unsigned long flags;
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void *linear_virt_addr;
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resource_size_t linear_phys_addr;
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size_t mtd_point_size;
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};
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static inline struct cramfs_sb_info *CRAMFS_SB(struct super_block *sb)
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{
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return sb->s_fs_info;
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}
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static const struct super_operations cramfs_ops;
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static const struct inode_operations cramfs_dir_inode_operations;
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static const struct file_operations cramfs_directory_operations;
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static const struct file_operations cramfs_physmem_fops;
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static const struct address_space_operations cramfs_aops;
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static DEFINE_MUTEX(read_mutex);
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/* These macros may change in future, to provide better st_ino semantics. */
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#define OFFSET(x) ((x)->i_ino)
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static unsigned long cramino(const struct cramfs_inode *cino, unsigned int offset)
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{
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if (!cino->offset)
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return offset + 1;
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if (!cino->size)
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return offset + 1;
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/*
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* The file mode test fixes buggy mkcramfs implementations where
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* cramfs_inode->offset is set to a non zero value for entries
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* which did not contain data, like devices node and fifos.
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*/
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switch (cino->mode & S_IFMT) {
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case S_IFREG:
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case S_IFDIR:
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case S_IFLNK:
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return cino->offset << 2;
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default:
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break;
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}
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return offset + 1;
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}
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static struct inode *get_cramfs_inode(struct super_block *sb,
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const struct cramfs_inode *cramfs_inode, unsigned int offset)
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{
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struct inode *inode;
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static struct timespec64 zerotime;
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inode = iget_locked(sb, cramino(cramfs_inode, offset));
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if (!inode)
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return ERR_PTR(-ENOMEM);
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if (!(inode->i_state & I_NEW))
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return inode;
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switch (cramfs_inode->mode & S_IFMT) {
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case S_IFREG:
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inode->i_fop = &generic_ro_fops;
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inode->i_data.a_ops = &cramfs_aops;
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if (IS_ENABLED(CONFIG_CRAMFS_MTD) &&
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CRAMFS_SB(sb)->flags & CRAMFS_FLAG_EXT_BLOCK_POINTERS &&
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CRAMFS_SB(sb)->linear_phys_addr)
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inode->i_fop = &cramfs_physmem_fops;
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break;
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case S_IFDIR:
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inode->i_op = &cramfs_dir_inode_operations;
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inode->i_fop = &cramfs_directory_operations;
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break;
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case S_IFLNK:
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inode->i_op = &page_symlink_inode_operations;
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inode_nohighmem(inode);
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inode->i_data.a_ops = &cramfs_aops;
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break;
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default:
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init_special_inode(inode, cramfs_inode->mode,
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old_decode_dev(cramfs_inode->size));
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}
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inode->i_mode = cramfs_inode->mode;
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i_uid_write(inode, cramfs_inode->uid);
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i_gid_write(inode, cramfs_inode->gid);
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/* if the lower 2 bits are zero, the inode contains data */
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if (!(inode->i_ino & 3)) {
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inode->i_size = cramfs_inode->size;
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inode->i_blocks = (cramfs_inode->size - 1) / 512 + 1;
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}
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/* Struct copy intentional */
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inode->i_mtime = inode->i_atime = inode->i_ctime = zerotime;
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/* inode->i_nlink is left 1 - arguably wrong for directories,
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but it's the best we can do without reading the directory
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contents. 1 yields the right result in GNU find, even
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without -noleaf option. */
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unlock_new_inode(inode);
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return inode;
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}
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/*
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* We have our own block cache: don't fill up the buffer cache
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* with the rom-image, because the way the filesystem is set
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* up the accesses should be fairly regular and cached in the
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* page cache and dentry tree anyway..
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*
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* This also acts as a way to guarantee contiguous areas of up to
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* BLKS_PER_BUF*PAGE_SIZE, so that the caller doesn't need to
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* worry about end-of-buffer issues even when decompressing a full
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* page cache.
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*
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* Note: This is all optimized away at compile time when
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* CONFIG_CRAMFS_BLOCKDEV=n.
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*/
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#define READ_BUFFERS (2)
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/* NEXT_BUFFER(): Loop over [0..(READ_BUFFERS-1)]. */
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#define NEXT_BUFFER(_ix) ((_ix) ^ 1)
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/*
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* BLKS_PER_BUF_SHIFT should be at least 2 to allow for "compressed"
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* data that takes up more space than the original and with unlucky
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* alignment.
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*/
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#define BLKS_PER_BUF_SHIFT (2)
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#define BLKS_PER_BUF (1 << BLKS_PER_BUF_SHIFT)
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#define BUFFER_SIZE (BLKS_PER_BUF*PAGE_SIZE)
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static unsigned char read_buffers[READ_BUFFERS][BUFFER_SIZE];
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static unsigned buffer_blocknr[READ_BUFFERS];
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static struct super_block *buffer_dev[READ_BUFFERS];
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static int next_buffer;
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/*
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* Populate our block cache and return a pointer to it.
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*/
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static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset,
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unsigned int len)
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{
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struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
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struct page *pages[BLKS_PER_BUF];
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unsigned i, blocknr, buffer;
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unsigned long devsize;
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char *data;
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if (!len)
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return NULL;
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blocknr = offset >> PAGE_SHIFT;
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offset &= PAGE_SIZE - 1;
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/* Check if an existing buffer already has the data.. */
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for (i = 0; i < READ_BUFFERS; i++) {
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unsigned int blk_offset;
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if (buffer_dev[i] != sb)
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continue;
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if (blocknr < buffer_blocknr[i])
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continue;
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blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_SHIFT;
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blk_offset += offset;
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if (blk_offset > BUFFER_SIZE ||
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blk_offset + len > BUFFER_SIZE)
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continue;
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return read_buffers[i] + blk_offset;
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}
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devsize = mapping->host->i_size >> PAGE_SHIFT;
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/* Ok, read in BLKS_PER_BUF pages completely first. */
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for (i = 0; i < BLKS_PER_BUF; i++) {
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struct page *page = NULL;
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if (blocknr + i < devsize) {
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page = read_mapping_page(mapping, blocknr + i, NULL);
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/* synchronous error? */
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if (IS_ERR(page))
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page = NULL;
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}
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pages[i] = page;
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}
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for (i = 0; i < BLKS_PER_BUF; i++) {
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struct page *page = pages[i];
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if (page) {
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wait_on_page_locked(page);
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if (!PageUptodate(page)) {
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/* asynchronous error */
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put_page(page);
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pages[i] = NULL;
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}
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}
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}
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buffer = next_buffer;
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next_buffer = NEXT_BUFFER(buffer);
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buffer_blocknr[buffer] = blocknr;
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buffer_dev[buffer] = sb;
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data = read_buffers[buffer];
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for (i = 0; i < BLKS_PER_BUF; i++) {
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struct page *page = pages[i];
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if (page) {
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memcpy(data, kmap(page), PAGE_SIZE);
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kunmap(page);
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put_page(page);
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} else
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memset(data, 0, PAGE_SIZE);
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data += PAGE_SIZE;
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}
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return read_buffers[buffer] + offset;
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}
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/*
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* Return a pointer to the linearly addressed cramfs image in memory.
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*/
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static void *cramfs_direct_read(struct super_block *sb, unsigned int offset,
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unsigned int len)
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{
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struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
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if (!len)
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return NULL;
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if (len > sbi->size || offset > sbi->size - len)
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return page_address(ZERO_PAGE(0));
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return sbi->linear_virt_addr + offset;
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}
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/*
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* Returns a pointer to a buffer containing at least LEN bytes of
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* filesystem starting at byte offset OFFSET into the filesystem.
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*/
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static void *cramfs_read(struct super_block *sb, unsigned int offset,
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unsigned int len)
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{
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struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
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if (IS_ENABLED(CONFIG_CRAMFS_MTD) && sbi->linear_virt_addr)
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return cramfs_direct_read(sb, offset, len);
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else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV))
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return cramfs_blkdev_read(sb, offset, len);
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else
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return NULL;
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}
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/*
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* For a mapping to be possible, we need a range of uncompressed and
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* contiguous blocks. Return the offset for the first block and number of
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* valid blocks for which that is true, or zero otherwise.
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*/
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static u32 cramfs_get_block_range(struct inode *inode, u32 pgoff, u32 *pages)
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{
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struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);
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int i;
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u32 *blockptrs, first_block_addr;
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/*
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* We can dereference memory directly here as this code may be
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* reached only when there is a direct filesystem image mapping
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* available in memory.
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*/
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blockptrs = (u32 *)(sbi->linear_virt_addr + OFFSET(inode) + pgoff * 4);
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first_block_addr = blockptrs[0] & ~CRAMFS_BLK_FLAGS;
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i = 0;
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do {
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u32 block_off = i * (PAGE_SIZE >> CRAMFS_BLK_DIRECT_PTR_SHIFT);
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u32 expect = (first_block_addr + block_off) |
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CRAMFS_BLK_FLAG_DIRECT_PTR |
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CRAMFS_BLK_FLAG_UNCOMPRESSED;
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if (blockptrs[i] != expect) {
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pr_debug("range: block %d/%d got %#x expects %#x\n",
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pgoff+i, pgoff + *pages - 1,
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blockptrs[i], expect);
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if (i == 0)
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return 0;
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break;
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}
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} while (++i < *pages);
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*pages = i;
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return first_block_addr << CRAMFS_BLK_DIRECT_PTR_SHIFT;
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}
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#ifdef CONFIG_MMU
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/*
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* Return true if the last page of a file in the filesystem image contains
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* some other data that doesn't belong to that file. It is assumed that the
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* last block is CRAMFS_BLK_FLAG_DIRECT_PTR | CRAMFS_BLK_FLAG_UNCOMPRESSED
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* (verified by cramfs_get_block_range() and directly accessible in memory.
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*/
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static bool cramfs_last_page_is_shared(struct inode *inode)
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{
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struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);
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u32 partial, last_page, blockaddr, *blockptrs;
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char *tail_data;
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partial = offset_in_page(inode->i_size);
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if (!partial)
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return false;
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last_page = inode->i_size >> PAGE_SHIFT;
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blockptrs = (u32 *)(sbi->linear_virt_addr + OFFSET(inode));
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blockaddr = blockptrs[last_page] & ~CRAMFS_BLK_FLAGS;
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blockaddr <<= CRAMFS_BLK_DIRECT_PTR_SHIFT;
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tail_data = sbi->linear_virt_addr + blockaddr + partial;
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return memchr_inv(tail_data, 0, PAGE_SIZE - partial) ? true : false;
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}
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static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma)
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{
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struct inode *inode = file_inode(file);
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struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);
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unsigned int pages, max_pages, offset;
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unsigned long address, pgoff = vma->vm_pgoff;
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char *bailout_reason;
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int ret;
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ret = generic_file_readonly_mmap(file, vma);
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if (ret)
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return ret;
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/*
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* Now try to pre-populate ptes for this vma with a direct
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* mapping avoiding memory allocation when possible.
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*/
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/* Could COW work here? */
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bailout_reason = "vma is writable";
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if (vma->vm_flags & VM_WRITE)
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goto bailout;
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max_pages = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
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bailout_reason = "beyond file limit";
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if (pgoff >= max_pages)
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goto bailout;
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pages = min(vma_pages(vma), max_pages - pgoff);
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offset = cramfs_get_block_range(inode, pgoff, &pages);
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bailout_reason = "unsuitable block layout";
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if (!offset)
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goto bailout;
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address = sbi->linear_phys_addr + offset;
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bailout_reason = "data is not page aligned";
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if (!PAGE_ALIGNED(address))
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goto bailout;
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/* Don't map the last page if it contains some other data */
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if (pgoff + pages == max_pages && cramfs_last_page_is_shared(inode)) {
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pr_debug("mmap: %s: last page is shared\n",
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file_dentry(file)->d_name.name);
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pages--;
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}
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if (!pages) {
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bailout_reason = "no suitable block remaining";
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goto bailout;
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}
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if (pages == vma_pages(vma)) {
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/*
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* The entire vma is mappable. remap_pfn_range() will
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* make it distinguishable from a non-direct mapping
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* in /proc/<pid>/maps by substituting the file offset
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* with the actual physical address.
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*/
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ret = remap_pfn_range(vma, vma->vm_start, address >> PAGE_SHIFT,
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pages * PAGE_SIZE, vma->vm_page_prot);
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} else {
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/*
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* Let's create a mixed map if we can't map it all.
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* The normal paging machinery will take care of the
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* unpopulated ptes via cramfs_readpage().
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*/
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int i;
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vma->vm_flags |= VM_MIXEDMAP;
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for (i = 0; i < pages && !ret; i++) {
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vm_fault_t vmf;
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unsigned long off = i * PAGE_SIZE;
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pfn_t pfn = phys_to_pfn_t(address + off, PFN_DEV);
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vmf = vmf_insert_mixed(vma, vma->vm_start + off, pfn);
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if (vmf & VM_FAULT_ERROR)
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ret = vm_fault_to_errno(vmf, 0);
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}
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}
|
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|
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if (!ret)
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pr_debug("mapped %s[%lu] at 0x%08lx (%u/%lu pages) "
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"to vma 0x%08lx, page_prot 0x%llx\n",
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file_dentry(file)->d_name.name, pgoff,
|
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address, pages, vma_pages(vma), vma->vm_start,
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(unsigned long long)pgprot_val(vma->vm_page_prot));
|
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return ret;
|
|
|
|
bailout:
|
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pr_debug("%s[%lu]: direct mmap impossible: %s\n",
|
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file_dentry(file)->d_name.name, pgoff, bailout_reason);
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/* Didn't manage any direct map, but normal paging is still possible */
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return 0;
|
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}
|
|
|
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#else /* CONFIG_MMU */
|
|
|
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static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma)
|
|
{
|
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return vma->vm_flags & (VM_SHARED | VM_MAYSHARE) ? 0 : -ENOSYS;
|
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}
|
|
|
|
static unsigned long cramfs_physmem_get_unmapped_area(struct file *file,
|
|
unsigned long addr, unsigned long len,
|
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unsigned long pgoff, unsigned long flags)
|
|
{
|
|
struct inode *inode = file_inode(file);
|
|
struct super_block *sb = inode->i_sb;
|
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struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
|
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unsigned int pages, block_pages, max_pages, offset;
|
|
|
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pages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
|
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max_pages = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
|
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if (pgoff >= max_pages || pages > max_pages - pgoff)
|
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return -EINVAL;
|
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block_pages = pages;
|
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offset = cramfs_get_block_range(inode, pgoff, &block_pages);
|
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if (!offset || block_pages != pages)
|
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return -ENOSYS;
|
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addr = sbi->linear_phys_addr + offset;
|
|
pr_debug("get_unmapped for %s ofs %#lx siz %lu at 0x%08lx\n",
|
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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);
|
|
|
|
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.val[0] = (u32)id;
|
|
buf->f_fsid.val[1] = (u32)(id >> 32);
|
|
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_readpage(struct file *file, struct page *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 = {
|
|
.readpage = cramfs_readpage
|
|
};
|
|
|
|
/*
|
|
* 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");
|