linux/fs/cramfs/inode.c
Linus Torvalds 511fb5bafe v6.6-vfs.super
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Merge tag 'v6.6-vfs.super' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull superblock updates from Christian Brauner:
 "This contains the super rework that was ready for this cycle. The
  first part changes the order of how we open block devices and allocate
  superblocks, contains various cleanups, simplifications, and a new
  mechanism to wait on superblock state changes.

  This unblocks work to ultimately limit the number of writers to a
  block device. Jan has already scheduled follow-up work that will be
  ready for v6.7 and allows us to restrict the number of writers to a
  given block device. That series builds on this work right here.

  The second part contains filesystem freezing updates.

  Overview:

  The generic superblock changes are rougly organized as follows
  (ignoring additional minor cleanups):

   (1) Removal of the bd_super member from struct block_device.

       This was a very odd back pointer to struct super_block with
       unclear rules. For all relevant places we have other means to get
       the same information so just get rid of this.

   (2) Simplify rules for superblock cleanup.

       Roughly, everything that is allocated during fs_context
       initialization and that's stored in fs_context->s_fs_info needs
       to be cleaned up by the fs_context->free() implementation before
       the superblock allocation function has been called successfully.

       After sget_fc() returned fs_context->s_fs_info has been
       transferred to sb->s_fs_info at which point sb->kill_sb() if
       fully responsible for cleanup. Adhering to these rules means that
       cleanup of sb->s_fs_info in fill_super() is to be avoided as it's
       brittle and inconsistent.

       Cleanup shouldn't be duplicated between sb->put_super() as
       sb->put_super() is only called if sb->s_root has been set aka
       when the filesystem has been successfully born (SB_BORN). That
       complexity should be avoided.

       This also means that block devices are to be closed in
       sb->kill_sb() instead of sb->put_super(). More details in the
       lower section.

   (3) Make it possible to lookup or create a superblock before opening
       block devices

       There's a subtle dependency on (2) as some filesystems did rely
       on fill_super() to be called in order to correctly clean up
       sb->s_fs_info. All these filesystems have been fixed.

   (4) Switch most filesystem to follow the same logic as the generic
       mount code now does as outlined in (3).

   (5) Use the superblock as the holder of the block device. We can now
       easily go back from block device to owning superblock.

   (6) Export and extend the generic fs_holder_ops and use them as
       holder ops everywhere and remove the filesystem specific holder
       ops.

   (7) Call from the block layer up into the filesystem layer when the
       block device is removed, allowing to shut down the filesystem
       without risk of deadlocks.

   (8) Get rid of get_super().

       We can now easily go back from the block device to owning
       superblock and can call up from the block layer into the
       filesystem layer when the device is removed. So no need to wade
       through all registered superblock to find the owning superblock
       anymore"

Link: https://lore.kernel.org/lkml/20230824-prall-intakt-95dbffdee4a0@brauner/

* tag 'v6.6-vfs.super' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (47 commits)
  super: use higher-level helper for {freeze,thaw}
  super: wait until we passed kill super
  super: wait for nascent superblocks
  super: make locking naming consistent
  super: use locking helpers
  fs: simplify invalidate_inodes
  fs: remove get_super
  block: call into the file system for ioctl BLKFLSBUF
  block: call into the file system for bdev_mark_dead
  block: consolidate __invalidate_device and fsync_bdev
  block: drop the "busy inodes on changed media" log message
  dasd: also call __invalidate_device when setting the device offline
  amiflop: don't call fsync_bdev in FDFMTBEG
  floppy: call disk_force_media_change when changing the format
  block: simplify the disk_force_media_change interface
  nbd: call blk_mark_disk_dead in nbd_clear_sock_ioctl
  xfs use fs_holder_ops for the log and RT devices
  xfs: drop s_umount over opening the log and RT devices
  ext4: use fs_holder_ops for the log device
  ext4: drop s_umount over opening the log device
  ...
2023-08-28 11:04:18 -07:00

1007 lines
26 KiB
C

/*
* 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_set_ctime_to_ts(inode,
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_from_page(data, page, 0, PAGE_SIZE);
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;
vm_flags_set(vma, 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 is_nommu_shared_mapping(vma->vm_flags) ? 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 = filemap_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);
generic_shutdown_super(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);
put_mtd_device(sb->s_mtd);
sb->s_mtd = NULL;
} else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV) && sb->s_bdev) {
sync_blockdev(sb->s_bdev);
blkdev_put(sb->s_bdev, 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_local_page(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_local(pgdata);
SetPageUptodate(page);
unlock_page(page);
return 0;
err:
kunmap_local(pgdata);
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");