[PATCH 12/23] initrd: switch initrd loading to struct file based APIs

Christoph Hellwig
2020-07-14T19:10:28Z

There is no good reason to mess with file descriptors from in-kernel
code, switch the initrd loading to struct file based read and writes
instead.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
fs/read_write.c | 2 +-
include/linux/syscalls.h | 1 -
init/do_mounts_rd.c | 82 ++++++++++++++++++++--------------------
3 files changed, 43 insertions(+), 42 deletions(-)

diff --git a/fs/read_write.c b/fs/read_write.c
index 4fb797822567a6..5db58b8c78d0dd 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -301,7 +301,7 @@ loff_t vfs_llseek(struct file *file, loff_t offset, int whence)
}
EXPORT_SYMBOL(vfs_llseek);

-off_t ksys_lseek(unsigned int fd, off_t offset, unsigned int whence)
+static off_t ksys_lseek(unsigned int fd, off_t offset, unsigned int whence)
{
off_t retval;
struct fd f = fdget_pos(fd);
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index b951a87da9877c..10843a6adb770d 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -1246,7 +1246,6 @@ int ksys_fchown(unsigned int fd, uid_t user, gid_t group);
int ksys_getdents64(unsigned int fd, struct linux_dirent64 __user *dirent,
unsigned int count);
int ksys_ioctl(unsigned int fd, unsigned int cmd, unsigned long arg);
-off_t ksys_lseek(unsigned int fd, off_t offset, unsigned int whence);
ssize_t ksys_read(unsigned int fd, char __user *buf, size_t count);
void ksys_sync(void);
int ksys_unshare(unsigned long unshare_flags);
diff --git a/init/do_mounts_rd.c b/init/do_mounts_rd.c
index 27b1bccf6f12a8..7b64390c075043 100644
--- a/init/do_mounts_rd.c
+++ b/init/do_mounts_rd.c
@@ -31,7 +31,8 @@ static int __init ramdisk_start_setup(char *str)
}
__setup("ramdisk_start=", ramdisk_start_setup);

-static int __init crd_load(int in_fd, int out_fd, decompress_fn deco);
+static int __init crd_load(struct file *in_file, struct file *out_file,
+ decompress_fn deco);

/*
* This routine tries to find a RAM disk image to load, and returns the
@@ -53,7 +54,8 @@ static int __init crd_load(int in_fd, int out_fd, decompress_fn deco);
* lz4
*/
static int __init
-identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor)
+identify_ramdisk_image(struct file *file, int start_block,
+ decompress_fn *decompressor)
{
const int size = 512;
struct minix_super_block *minixsb;
@@ -64,6 +66,7 @@ identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor)
unsigned char *buf;
const char *compress_name;
unsigned long n;
+ loff_t pos;

buf = kmalloc(size, GFP_KERNEL);
if (!buf)
@@ -78,8 +81,8 @@ identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor)
/*
* Read block 0 to test for compressed kernel
*/
- ksys_lseek(fd, start_block * BLOCK_SIZE, 0);
- ksys_read(fd, buf, size);
+ pos = start_block * BLOCK_SIZE;
+ kernel_read(file, buf, size, &pos);

*decompressor = decompress_method(buf, size, &compress_name);
if (compress_name) {
@@ -124,8 +127,8 @@ identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor)
/*
* Read 512 bytes further to check if cramfs is padded
*/
- ksys_lseek(fd, start_block * BLOCK_SIZE + 0x200, 0);
- ksys_read(fd, buf, size);
+ pos = start_block * BLOCK_SIZE + 0x200;
+ kernel_read(file, buf, size, &pos);

if (cramfsb->magic == CRAMFS_MAGIC) {
printk(KERN_NOTICE
@@ -138,8 +141,8 @@ identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor)
/*
* Read block 1 to test for minix and ext2 superblock
*/
- ksys_lseek(fd, (start_block+1) * BLOCK_SIZE, 0);
- ksys_read(fd, buf, size);
+ pos = (start_block + 1) * BLOCK_SIZE;
+ kernel_read(file, buf, size, &pos);

/* Try minix */
if (minixsb->s_magic == MINIX_SUPER_MAGIC ||
@@ -166,15 +169,23 @@ identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor)
start_block);

done:
- ksys_lseek(fd, start_block * BLOCK_SIZE, 0);
kfree(buf);
return nblocks;
}

+static unsigned long nr_blocks(struct file *file)
+{
+ struct inode *inode = file->f_mapping->host;
+
+ if (!S_ISBLK(inode->i_mode))
+ return 0;
+ return i_size_read(inode) >> 10;
+}
+
int __init rd_load_image(char *from)
{
int res = 0;
- int in_fd, out_fd;
+ struct file *in_file, *out_file;
unsigned long rd_blocks, devblocks;
int nblocks, i;
char *buf = NULL;
@@ -184,20 +195,20 @@ int __init rd_load_image(char *from)
char rotator[4] = { '|' , '/' , '-' , '\\' };
#endif

- out_fd = ksys_open("/dev/ram", O_RDWR, 0);
- if (out_fd < 0)
+ out_file = filp_open("/dev/ram", O_RDWR, 0);
+ if (IS_ERR(out_file))
goto out;

- in_fd = ksys_open(from, O_RDONLY, 0);
- if (in_fd < 0)
+ in_file = filp_open(from, O_RDONLY, 0);
+ if (IS_ERR(in_file))
goto noclose_input;

- nblocks = identify_ramdisk_image(in_fd, rd_image_start, &decompressor);
+ nblocks = identify_ramdisk_image(in_file, rd_image_start, &decompressor);
if (nblocks < 0)
goto done;

if (nblocks == 0) {
- if (crd_load(in_fd, out_fd, decompressor) == 0)
+ if (crd_load(in_file, out_file, decompressor) == 0)
goto successful_load;
goto done;
}
@@ -206,11 +217,7 @@ int __init rd_load_image(char *from)
* NOTE NOTE: nblocks is not actually blocks but
* the number of kibibytes of data to load into a ramdisk.
*/
- if (ksys_ioctl(out_fd, BLKGETSIZE, (unsigned long)&rd_blocks) < 0)
- rd_blocks = 0;
- else
- rd_blocks >>= 1;
-
+ rd_blocks = nr_blocks(out_file);
if (nblocks > rd_blocks) {
printk("RAMDISK: image too big! (%dKiB/%ldKiB)\n",
nblocks, rd_blocks);
@@ -220,13 +227,10 @@ int __init rd_load_image(char *from)
/*
* OK, time to copy in the data
*/
- if (ksys_ioctl(in_fd, BLKGETSIZE, (unsigned long)&devblocks) < 0)
- devblocks = 0;
- else
- devblocks >>= 1;
-
if (strcmp(from, "/initrd.image") == 0)
devblocks = nblocks;
+ else
+ devblocks = nr_blocks(in_file);

if (devblocks == 0) {
printk(KERN_ERR "RAMDISK: could not determine device size\n");
@@ -245,14 +249,11 @@ int __init rd_load_image(char *from)
if (i && (i % devblocks == 0)) {
pr_cont("done disk #1.\n");
rotate = 0;
- if (ksys_close(in_fd)) {
- printk("Error closing the disk.\n");
- goto noclose_input;
- }
+ fput(in_file);
break;
}
- ksys_read(in_fd, buf, BLOCK_SIZE);
- ksys_write(out_fd, buf, BLOCK_SIZE);
+ kernel_read(in_file, buf, BLOCK_SIZE, &in_file->f_pos);
+ kernel_write(out_file, buf, BLOCK_SIZE, &out_file->f_pos);
#if !defined(CONFIG_S390)
if (!(i % 16)) {
pr_cont("%c\b", rotator[rotate & 0x3]);
@@ -265,9 +266,9 @@ int __init rd_load_image(char *from)
successful_load:
res = 1;
done:
- ksys_close(in_fd);
+ fput(in_file);
noclose_input:
- ksys_close(out_fd);
+ fput(out_file);
out:
kfree(buf);
ksys_unlink("/dev/ram");
@@ -283,11 +284,11 @@ int __init rd_load_disk(int n)

static int exit_code;
static int decompress_error;
-static int crd_infd, crd_outfd;
+static struct file *crd_infile, *crd_outfile;

static long __init compr_fill(void *buf, unsigned long len)
{
- long r = ksys_read(crd_infd, buf, len);
+ long r = kernel_read(crd_infile, buf, len, &crd_infile->f_pos);
if (r < 0)
printk(KERN_ERR "RAMDISK: error while reading compressed data");
else if (r == 0)
@@ -297,7 +298,7 @@ static long __init compr_fill(void *buf, unsigned long len)

static long __init compr_flush(void *window, unsigned long outcnt)
{
- long written = ksys_write(crd_outfd, window, outcnt);
+ long written = kernel_write(crd_outfile, window, outcnt, &crd_outfile->f_pos);
if (written != outcnt) {
if (decompress_error == 0)
printk(KERN_ERR
@@ -316,11 +317,12 @@ static void __init error(char *x)
decompress_error = 1;
}

-static int __init crd_load(int in_fd, int out_fd, decompress_fn deco)
+static int __init crd_load(struct file *in_file, struct file *out_file,
+ decompress_fn deco)
{
int result;
- crd_infd = in_fd;
- crd_outfd = out_fd;
+ crd_infile = in_file;
+ crd_outfile = out_file;

if (!deco) {
pr_emerg("Invalid ramdisk decompression routine. "
--
2.27.0