/*
* 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 buffer_head * bh_array[BLKS_PER_BUF];
unsigned i, blocknr, buffer;
char *data;
if (!len)
return NULL;
blocknr = offset >> PAGE_CACHE_SHIFT;
offset &= PAGE_CACHE_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_CACHE_SHIFT;
blk_offset += offset;
if (blk_offset + len > BUFFER_SIZE)
continue;
return read_buffers[i] + blk_offset;
}
/* Ok, read in BLKS_PER_BUF pages completely first. */
for (i = 0; i < BLKS_PER_BUF; i++)
bh_array[i] = bread(sb->s_dev, blocknr + i, PAGE_CACHE_SIZE);
/* Ok, copy them to the staging area without sleeping. */
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 buffer_head * bh = bh_array[i];
if (bh) {
memcpy(data, bh->b_data, PAGE_CACHE_SIZE);
bforget(bh);
} else
memset(data, 0, PAGE_CACHE_SIZE);
data += PAGE_CACHE_SIZE;
}
return read_buffers[buffer] + 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 buffer_head * bh_array[BLKS_PER_BUF];
struct buffer_head * read_array[BLKS_PER_BUF];
unsigned i, blocknr, buffer, unread;
unsigned long devsize;
int major, minor;
char *data;
if (!len)
return NULL;
blocknr = offset >> PAGE_CACHE_SHIFT;
offset &= PAGE_CACHE_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_CACHE_SHIFT;
blk_offset += offset;
if (blk_offset + len > BUFFER_SIZE)
continue;
return read_buffers[i] + blk_offset;
}
devsize = ~0UL;
major = MAJOR(sb->s_dev);
minor = MINOR(sb->s_dev);
if (blk_size[major])
devsize = blk_size[major][minor] >> 2;
/* Ok, read in BLKS_PER_BUF pages completely first. */
unread = 0;
for (i = 0; i < BLKS_PER_BUF; i++) {
struct buffer_head *bh;
bh = NULL;
if (blocknr + i < devsize) {
bh = sb_getblk(sb, blocknr + i);
if (!buffer_uptodate(bh))
read_array[unread++] = bh;
}
bh_array[i] = bh;
}
if (unread) {
ll_rw_block(READ, unread, read_array);
do {
unread--;
wait_on_buffer(read_array[unread]);
} while (unread);
}
/* Ok, copy them to the staging area without sleeping. */
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 buffer_head * bh = bh_array[i];
if (bh) {
memcpy(data, bh->b_data, PAGE_CACHE_SIZE);
brelse(bh);
} else
memset(data, 0, PAGE_CACHE_SIZE);
data += PAGE_CACHE_SIZE;
}
return read_buffers[buffer] + 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_comm(struct super_block *sb, unsigned int offset, unsigned int len)
{
struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
struct page *pages[BLKS_PER_BUF];
unsigned i, blocknr, buffer;
unsigned long devsize;
char *data;
if (!len)
return NULL;
blocknr = offset >> PAGE_CACHE_SHIFT;
offset &= PAGE_CACHE_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_CACHE_SHIFT;
blk_offset += offset;
if (blk_offset + len > BUFFER_SIZE)
continue;
return read_buffers[i] + blk_offset;
}
devsize = mapping->host->i_size >> PAGE_CACHE_SHIFT;
/* Ok, read in BLKS_PER_BUF pages completely first. */
for (i = 0; i < BLKS_PER_BUF; i++) {
struct page *page = NULL;
if (blocknr + i < devsize) {
page = read_mapping_page_async(mapping, blocknr + i,
NULL);
/* synchronous error? */
if (IS_ERR(page))
page = NULL;
}
pages[i] = page;
}
for (i = 0; i < BLKS_PER_BUF; i++) {
struct page *page = pages[i];
if (page) {
wait_on_page_locked(page);
if (!PageUptodate(page)) {
/* asynchronous error */
page_cache_release(page);
pages[i] = NULL;
}
}
}
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_CACHE_SIZE);
kunmap(page);
page_cache_release(page);
} else
memset(data, 0, PAGE_CACHE_SIZE);
data += PAGE_CACHE_SIZE;
}
return read_buffers[buffer] + offset;
}
