/**
* nilfs_copy_buffer -- copy buffer data and flags
* @dbh: destination buffer
* @sbh: source buffer
*/
void nilfs_copy_buffer(struct buffer_head *dbh, struct buffer_head *sbh)
{
void *kaddr0, *kaddr1;
unsigned long bits;
struct page *spage = sbh->b_page, *dpage = dbh->b_page;
struct buffer_head *bh;
kaddr0 = kmap_atomic(spage);
kaddr1 = kmap_atomic(dpage);
memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size);
kunmap_atomic(kaddr1);
kunmap_atomic(kaddr0);
dbh->b_state = sbh->b_state & NILFS_BUFFER_INHERENT_BITS;
dbh->b_blocknr = sbh->b_blocknr;
dbh->b_bdev = sbh->b_bdev;
bh = dbh;
bits = sbh->b_state & (BIT(BH_Uptodate) | BIT(BH_Mapped));
while ((bh = bh->b_this_page) != dbh) {
lock_buffer(bh);
bits &= bh->b_state;
unlock_buffer(bh);
}
if (bits & BIT(BH_Uptodate))
SetPageUptodate(dpage);
else
ClearPageUptodate(dpage);
if (bits & BIT(BH_Mapped))
SetPageMappedToDisk(dpage);
else
ClearPageMappedToDisk(dpage);
}
static int nilfs_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct page *page = vmf->page;
struct inode *inode = vma->vm_file->f_dentry->d_inode;
struct nilfs_transaction_info ti;
int ret;
if (unlikely(nilfs_near_disk_full(inode->i_sb->s_fs_info)))
return VM_FAULT_SIGBUS;
lock_page(page);
if (page->mapping != inode->i_mapping ||
page_offset(page) >= i_size_read(inode) || !PageUptodate(page)) {
unlock_page(page);
return VM_FAULT_NOPAGE;
}
if (PageMappedToDisk(page))
goto mapped;
if (page_has_buffers(page)) {
struct buffer_head *bh, *head;
int fully_mapped = 1;
bh = head = page_buffers(page);
do {
if (!buffer_mapped(bh)) {
fully_mapped = 0;
break;
}
} while (bh = bh->b_this_page, bh != head);
if (fully_mapped) {
SetPageMappedToDisk(page);
goto mapped;
}
}
unlock_page(page);
ret = nilfs_transaction_begin(inode->i_sb, &ti, 1);
if (unlikely(ret))
return VM_FAULT_SIGBUS;
ret = block_page_mkwrite(vma, vmf, nilfs_get_block);
if (ret != VM_FAULT_LOCKED) {
nilfs_transaction_abort(inode->i_sb);
return ret;
}
nilfs_set_file_dirty(inode, 1 << (PAGE_SHIFT - inode->i_blkbits));
nilfs_transaction_commit(inode->i_sb);
mapped:
wait_on_page_writeback(page);
return VM_FAULT_LOCKED;
}
/**
* nilfs_copy_page -- copy the page with buffers
* @dst: destination page
* @src: source page
* @copy_dirty: flag whether to copy dirty states on the page's buffer heads.
*
* This function is for both data pages and btnode pages. The dirty flag
* should be treated by caller. The page must not be under i/o.
* Both src and dst page must be locked
*/
static void nilfs_copy_page(struct page *dst, struct page *src, int copy_dirty)
{
struct buffer_head *dbh, *dbufs, *sbh, *sbufs;
unsigned long mask = NILFS_BUFFER_INHERENT_BITS;
BUG_ON(PageWriteback(dst));
sbh = sbufs = page_buffers(src);
if (!page_has_buffers(dst))
create_empty_buffers(dst, sbh->b_size, 0);
if (copy_dirty)
mask |= BIT(BH_Dirty);
dbh = dbufs = page_buffers(dst);
do {
lock_buffer(sbh);
lock_buffer(dbh);
dbh->b_state = sbh->b_state & mask;
dbh->b_blocknr = sbh->b_blocknr;
dbh->b_bdev = sbh->b_bdev;
sbh = sbh->b_this_page;
dbh = dbh->b_this_page;
} while (dbh != dbufs);
copy_highpage(dst, src);
if (PageUptodate(src) && !PageUptodate(dst))
SetPageUptodate(dst);
else if (!PageUptodate(src) && PageUptodate(dst))
ClearPageUptodate(dst);
if (PageMappedToDisk(src) && !PageMappedToDisk(dst))
SetPageMappedToDisk(dst);
else if (!PageMappedToDisk(src) && PageMappedToDisk(dst))
ClearPageMappedToDisk(dst);
do {
unlock_buffer(sbh);
unlock_buffer(dbh);
sbh = sbh->b_this_page;
dbh = dbh->b_this_page;
} while (dbh != dbufs);
}
int ext4_mpage_readpages(struct address_space *mapping,
struct list_head *pages, struct page *page,
unsigned nr_pages, bool is_readahead)
{
struct bio *bio = NULL;
sector_t last_block_in_bio = 0;
struct inode *inode = mapping->host;
const unsigned blkbits = inode->i_blkbits;
const unsigned blocks_per_page = PAGE_SIZE >> blkbits;
const unsigned blocksize = 1 << blkbits;
sector_t block_in_file;
sector_t last_block;
sector_t last_block_in_file;
sector_t blocks[MAX_BUF_PER_PAGE];
unsigned page_block;
struct block_device *bdev = inode->i_sb->s_bdev;
int length;
unsigned relative_block = 0;
struct ext4_map_blocks map;
map.m_pblk = 0;
map.m_lblk = 0;
map.m_len = 0;
map.m_flags = 0;
for (; nr_pages; nr_pages--) {
int fully_mapped = 1;
unsigned first_hole = blocks_per_page;
prefetchw(&page->flags);
if (pages) {
page = lru_to_page(pages);
list_del(&page->lru);
if (add_to_page_cache_lru(page, mapping, page->index,
readahead_gfp_mask(mapping)))
goto next_page;
}
if (page_has_buffers(page))
goto confused;
block_in_file = (sector_t)page->index << (PAGE_SHIFT - blkbits);
last_block = block_in_file + nr_pages * blocks_per_page;
last_block_in_file = (i_size_read(inode) + blocksize - 1) >> blkbits;
if (last_block > last_block_in_file)
last_block = last_block_in_file;
page_block = 0;
/*
* Map blocks using the previous result first.
*/
if ((map.m_flags & EXT4_MAP_MAPPED) &&
block_in_file > map.m_lblk &&
block_in_file < (map.m_lblk + map.m_len)) {
unsigned map_offset = block_in_file - map.m_lblk;
unsigned last = map.m_len - map_offset;
for (relative_block = 0; ; relative_block++) {
if (relative_block == last) {
/* needed? */
map.m_flags &= ~EXT4_MAP_MAPPED;
break;
}
if (page_block == blocks_per_page)
break;
blocks[page_block] = map.m_pblk + map_offset +
relative_block;
page_block++;
block_in_file++;
}
}
/*
* Then do more ext4_map_blocks() calls until we are
* done with this page.
*/
while (page_block < blocks_per_page) {
if (block_in_file < last_block) {
map.m_lblk = block_in_file;
map.m_len = last_block - block_in_file;
if (ext4_map_blocks(NULL, inode, &map, 0) < 0) {
set_error_page:
SetPageError(page);
zero_user_segment(page, 0,
PAGE_SIZE);
unlock_page(page);
goto next_page;
}
}
if ((map.m_flags & EXT4_MAP_MAPPED) == 0) {
fully_mapped = 0;
if (first_hole == blocks_per_page)
first_hole = page_block;
page_block++;
block_in_file++;
continue;
}
if (first_hole != blocks_per_page)
goto confused; /* hole -> non-hole */
/* Contiguous blocks? */
if (page_block && blocks[page_block-1] != map.m_pblk-1)
goto confused;
for (relative_block = 0; ; relative_block++) {
if (relative_block == map.m_len) {
/* needed? */
map.m_flags &= ~EXT4_MAP_MAPPED;
break;
} else if (page_block == blocks_per_page)
break;
blocks[page_block] = map.m_pblk+relative_block;
page_block++;
block_in_file++;
}
}
if (first_hole != blocks_per_page) {
zero_user_segment(page, first_hole << blkbits,
PAGE_SIZE);
if (first_hole == 0) {
SetPageUptodate(page);
unlock_page(page);
goto next_page;
}
} else if (fully_mapped) {
SetPageMappedToDisk(page);
}
if (fully_mapped && blocks_per_page == 1 &&
!PageUptodate(page) && cleancache_get_page(page) == 0) {
SetPageUptodate(page);
goto confused;
}
/*
* This page will go to BIO. Do we need to send this
* BIO off first?
*/
if (bio && (last_block_in_bio != blocks[0] - 1)) {
submit_and_realloc:
submit_bio(bio);
bio = NULL;
}
if (bio == NULL) {
struct fscrypt_ctx *ctx = NULL;
if (IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode)) {
ctx = fscrypt_get_ctx(inode, GFP_NOFS);
if (IS_ERR(ctx))
goto set_error_page;
}
bio = bio_alloc(GFP_KERNEL,
min_t(int, nr_pages, BIO_MAX_PAGES));
if (!bio) {
if (ctx)
fscrypt_release_ctx(ctx);
goto set_error_page;
}
bio_set_dev(bio, bdev);
bio->bi_iter.bi_sector = blocks[0] << (blkbits - 9);
bio->bi_end_io = mpage_end_io;
bio->bi_private = ctx;
bio_set_op_attrs(bio, REQ_OP_READ,
is_readahead ? REQ_RAHEAD : 0);
}
length = first_hole << blkbits;
if (bio_add_page(bio, page, length, 0) < length)
goto submit_and_realloc;
if (((map.m_flags & EXT4_MAP_BOUNDARY) &&
(relative_block == map.m_len)) ||
(first_hole != blocks_per_page)) {
submit_bio(bio);
bio = NULL;
} else
last_block_in_bio = blocks[blocks_per_page - 1];
goto next_page;
confused:
if (bio) {
submit_bio(bio);
bio = NULL;
}
if (!PageUptodate(page))
block_read_full_page(page, ext4_get_block);
else
unlock_page(page);
next_page:
if (pages)
put_page(page);
}
BUG_ON(pages && !list_empty(pages));
if (bio)
submit_bio(bio);
return 0;
}
/*
* This is the worker routine which does all the work of mapping the disk
* blocks and constructs largest possible bios, submits them for IO if the
* blocks are not contiguous on the disk.
*
* We pass a buffer_head back and forth and use its buffer_mapped() flag to
* represent the validity of its disk mapping and to decide when to do the next
* get_block() call.
*/
static struct bio *
do_mpage_readpage(struct bio *bio, struct page *page, unsigned nr_pages,
sector_t *last_block_in_bio, struct buffer_head *map_bh,
unsigned long *first_logical_block, get_block_t get_block)
{
struct inode *inode = page->mapping->host;
const unsigned blkbits = inode->i_blkbits;
const unsigned blocks_per_page = PAGE_CACHE_SIZE >> blkbits;
const unsigned blocksize = 1 << blkbits;
sector_t block_in_file;
sector_t last_block;
sector_t last_block_in_file;
sector_t blocks[MAX_BUF_PER_PAGE];
unsigned page_block;
unsigned first_hole = blocks_per_page;
struct block_device *bdev = NULL;
int length;
int fully_mapped = 1;
unsigned nblocks;
unsigned relative_block;
if (page_has_buffers(page))
goto confused;
block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits);
last_block = block_in_file + nr_pages * blocks_per_page;
last_block_in_file = (i_size_read(inode) + blocksize - 1) >> blkbits;
if (last_block > last_block_in_file)
last_block = last_block_in_file;
page_block = 0;
/*
* Map blocks using the result from the previous get_blocks call first.
*/
nblocks = map_bh->b_size >> blkbits;
if (buffer_mapped(map_bh) && block_in_file > *first_logical_block &&
block_in_file < (*first_logical_block + nblocks)) {
unsigned map_offset = block_in_file - *first_logical_block;
unsigned last = nblocks - map_offset;
for (relative_block = 0; ; relative_block++) {
if (relative_block == last) {
clear_buffer_mapped(map_bh);
break;
}
if (page_block == blocks_per_page)
break;
blocks[page_block] = map_bh->b_blocknr + map_offset +
relative_block;
page_block++;
block_in_file++;
}
bdev = map_bh->b_bdev;
}
/*
* Then do more get_blocks calls until we are done with this page.
*/
map_bh->b_page = page;
while (page_block < blocks_per_page) {
map_bh->b_state = 0;
map_bh->b_size = 0;
if (block_in_file < last_block) {
map_bh->b_size = (last_block-block_in_file) << blkbits;
if (get_block(inode, block_in_file, map_bh, 0))
goto confused;
*first_logical_block = block_in_file;
}
if (!buffer_mapped(map_bh)) {
fully_mapped = 0;
if (first_hole == blocks_per_page)
first_hole = page_block;
page_block++;
block_in_file++;
continue;
}
/* some filesystems will copy data into the page during
* the get_block call, in which case we don't want to
* read it again. map_buffer_to_page copies the data
* we just collected from get_block into the page's buffers
* so readpage doesn't have to repeat the get_block call
*/
if (buffer_uptodate(map_bh)) {
map_buffer_to_page(page, map_bh, page_block);
goto confused;
}
if (first_hole != blocks_per_page)
goto confused; /* hole -> non-hole */
/* Contiguous blocks? */
if (page_block && blocks[page_block-1] != map_bh->b_blocknr-1)
goto confused;
nblocks = map_bh->b_size >> blkbits;
for (relative_block = 0; ; relative_block++) {
if (relative_block == nblocks) {
clear_buffer_mapped(map_bh);
break;
} else if (page_block == blocks_per_page)
break;
blocks[page_block] = map_bh->b_blocknr+relative_block;
page_block++;
block_in_file++;
}
bdev = map_bh->b_bdev;
}
if (first_hole != blocks_per_page) {
zero_user_segment(page, first_hole << blkbits, PAGE_CACHE_SIZE);
if (first_hole == 0) {
SetPageUptodate(page);
unlock_page(page);
goto out;
}
} else if (fully_mapped) {
SetPageMappedToDisk(page);
}
if (fully_mapped && blocks_per_page == 1 && !PageUptodate(page) &&
cleancache_get_page(page) == 0) {
SetPageUptodate(page);
goto confused;
}
/*
* This page will go to BIO. Do we need to send this BIO off first?
*/
if (bio && (*last_block_in_bio != blocks[0] - 1))
bio = mpage_bio_submit(READ, bio);
alloc_new:
if (bio == NULL) {
bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9),
min_t(int, nr_pages, bio_get_nr_vecs(bdev)),
GFP_KERNEL);
if (bio == NULL)
goto confused;
}
static int nilfs_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct page *page = vmf->page;
struct inode *inode = file_inode(vma->vm_file);
struct nilfs_transaction_info ti;
int ret = 0;
if (unlikely(nilfs_near_disk_full(inode->i_sb->s_fs_info)))
return VM_FAULT_SIGBUS; /* -ENOSPC */
sb_start_pagefault(inode->i_sb);
lock_page(page);
if (page->mapping != inode->i_mapping ||
page_offset(page) >= i_size_read(inode) || !PageUptodate(page)) {
unlock_page(page);
ret = -EFAULT; /* make the VM retry the fault */
goto out;
}
/*
* check to see if the page is mapped already (no holes)
*/
if (PageMappedToDisk(page))
goto mapped;
if (page_has_buffers(page)) {
struct buffer_head *bh, *head;
int fully_mapped = 1;
bh = head = page_buffers(page);
do {
if (!buffer_mapped(bh)) {
fully_mapped = 0;
break;
}
} while (bh = bh->b_this_page, bh != head);
if (fully_mapped) {
SetPageMappedToDisk(page);
goto mapped;
}
}
unlock_page(page);
/*
* fill hole blocks
*/
ret = nilfs_transaction_begin(inode->i_sb, &ti, 1);
/* never returns -ENOMEM, but may return -ENOSPC */
if (unlikely(ret))
goto out;
file_update_time(vma->vm_file);
ret = __block_page_mkwrite(vma, vmf, nilfs_get_block);
if (ret) {
nilfs_transaction_abort(inode->i_sb);
goto out;
}
nilfs_set_file_dirty(inode, 1 << (PAGE_SHIFT - inode->i_blkbits));
nilfs_transaction_commit(inode->i_sb);
mapped:
wait_for_stable_page(page);
out:
sb_end_pagefault(inode->i_sb);
return block_page_mkwrite_return(ret);
}
/*
* This function was originally taken from fs/mpage.c, and customized for f2fs.
* Major change was from block_size == page_size in f2fs by default.
*/
static int f2fs_mpage_readpages(struct address_space *mapping,
struct list_head *pages, struct page *page,
unsigned nr_pages)
{
struct bio *bio = NULL;
unsigned page_idx;
sector_t last_block_in_bio = 0;
struct inode *inode = mapping->host;
const unsigned blkbits = inode->i_blkbits;
const unsigned blocksize = 1 << blkbits;
sector_t block_in_file;
sector_t last_block;
sector_t last_block_in_file;
sector_t block_nr;
struct block_device *bdev = inode->i_sb->s_bdev;
struct f2fs_map_blocks map;
map.m_pblk = 0;
map.m_lblk = 0;
map.m_len = 0;
map.m_flags = 0;
for (page_idx = 0; nr_pages; page_idx++, nr_pages--) {
prefetchw(&page->flags);
if (pages) {
page = list_entry(pages->prev, struct page, lru);
list_del(&page->lru);
if (add_to_page_cache_lru(page, mapping,
page->index, GFP_KERNEL))
goto next_page;
}
block_in_file = (sector_t)page->index;
last_block = block_in_file + nr_pages;
last_block_in_file = (i_size_read(inode) + blocksize - 1) >>
blkbits;
if (last_block > last_block_in_file)
last_block = last_block_in_file;
/*
* Map blocks using the previous result first.
*/
if ((map.m_flags & F2FS_MAP_MAPPED) &&
block_in_file > map.m_lblk &&
block_in_file < (map.m_lblk + map.m_len))
goto got_it;
/*
* Then do more f2fs_map_blocks() calls until we are
* done with this page.
*/
map.m_flags = 0;
if (block_in_file < last_block) {
map.m_lblk = block_in_file;
map.m_len = last_block - block_in_file;
if (f2fs_map_blocks(inode, &map, 0, false))
goto set_error_page;
}
got_it:
if ((map.m_flags & F2FS_MAP_MAPPED)) {
block_nr = map.m_pblk + block_in_file - map.m_lblk;
SetPageMappedToDisk(page);
if (!PageUptodate(page) && !cleancache_get_page(page)) {
SetPageUptodate(page);
goto confused;
}
} else {
zero_user_segment(page, 0, PAGE_CACHE_SIZE);
SetPageUptodate(page);
unlock_page(page);
goto next_page;
}
/*
* This page will go to BIO. Do we need to send this
* BIO off first?
*/
if (bio && (last_block_in_bio != block_nr - 1)) {
submit_and_realloc:
submit_bio(READ, bio);
bio = NULL;
}
if (bio == NULL) {
struct f2fs_crypto_ctx *ctx = NULL;
if (f2fs_encrypted_inode(inode) &&
S_ISREG(inode->i_mode)) {
struct page *cpage;
ctx = f2fs_get_crypto_ctx(inode);
if (IS_ERR(ctx))
goto set_error_page;
/* wait the page to be moved by cleaning */
cpage = find_lock_page(
META_MAPPING(F2FS_I_SB(inode)),
block_nr);
if (cpage) {
f2fs_wait_on_page_writeback(cpage,
DATA);
f2fs_put_page(cpage, 1);
}
}
bio = bio_alloc(GFP_KERNEL,
min_t(int, nr_pages, BIO_MAX_PAGES));
if (!bio) {
if (ctx)
f2fs_release_crypto_ctx(ctx);
goto set_error_page;
}
bio->bi_bdev = bdev;
bio->bi_iter.bi_sector = SECTOR_FROM_BLOCK(block_nr);
bio->bi_end_io = f2fs_read_end_io;
bio->bi_private = ctx;
}
if (bio_add_page(bio, page, blocksize, 0) < blocksize)
goto submit_and_realloc;
last_block_in_bio = block_nr;
goto next_page;
set_error_page:
SetPageError(page);
zero_user_segment(page, 0, PAGE_CACHE_SIZE);
unlock_page(page);
goto next_page;
confused:
if (bio) {
submit_bio(READ, bio);
bio = NULL;
}
unlock_page(page);
next_page:
if (pages)
page_cache_release(page);
}
BUG_ON(pages && !list_empty(pages));
if (bio)
submit_bio(READ, bio);
return 0;
}
/*
* This is the worker routine which does all the work of mapping the disk
* blocks and constructs largest possible bios, submits them for IO if the
* blocks are not contiguous on the disk.
*
* We pass a buffer_head back and forth and use its buffer_mapped() flag to
* represent the validity of its disk mapping and to decide when to do the next
* get_block() call.
*/
static struct bio *
do_mpage_readpage(struct bio *bio, struct page *page, unsigned nr_pages,
sector_t *last_block_in_bio, struct buffer_head *map_bh,
unsigned long *first_logical_block, struct compressed_bio **cb, get_block_t get_block)
{
struct inode *inode = page->mapping->host;
const unsigned blkbits = inode->i_blkbits;
const unsigned blocks_per_page = PAGE_CACHE_SIZE >> blkbits; //SET TO 1
const unsigned blocksize = 1 << blkbits;
sector_t block_in_file;
sector_t last_block;
sector_t last_block_in_file;
sector_t blocks[MAX_BUF_PER_PAGE];
unsigned page_block; //Increments to 1
unsigned first_hole = blocks_per_page;
struct block_device *bdev = NULL;
int fully_mapped = 1;
unsigned nblocks;
unsigned relative_block;
int err;
/* blkbits = 12 | MAX_BUF_PER_PAGE = 8 */
if (page_has_buffers(page))
goto confused;
/* block_in_file : page->index
* last_block : last page->index of requested nr_pages
* last_block_in_file : always index of last_page_of_file
*/
block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits);
last_block = block_in_file + nr_pages * blocks_per_page;
last_block_in_file = (i_size_read(inode) + blocksize - 1) >> blkbits;
if (last_block > last_block_in_file)
last_block = last_block_in_file;
page_block = 0;
/*
* Map blocks using the result from the previous get_blocks call first.
*/
/* nblocks : Initially 0 | Later mapped to 1 extent so is mostly 16 */
nblocks = map_bh->b_size >> blkbits;
printk(KERN_INFO "\ncurrent_page : %Lu | nblocks_initial : %u", block_in_file, nblocks);
if (buffer_mapped(map_bh) && block_in_file > *first_logical_block &&
block_in_file < (*first_logical_block + nblocks)) {
unsigned map_offset = block_in_file - *first_logical_block;
unsigned last = nblocks - map_offset;
for (relative_block = 0; ; relative_block++) {
if (relative_block == last) {
clear_buffer_mapped(map_bh);
break;
}
if (page_block == blocks_per_page)
break;
blocks[page_block] = map_bh->b_blocknr + map_offset +
relative_block;
page_block++;
block_in_file++;
}
bdev = map_bh->b_bdev;
}
/*
* Then do more get_blocks calls until we are done with this page.
*/
map_bh->b_page = page;
while (page_block < blocks_per_page) {
map_bh->b_state = 0;
map_bh->b_size = 0;
if (block_in_file < last_block) {
map_bh->b_size = (last_block - block_in_file) << blkbits;
/* use of get_block => ***needs buffer_head map_bh
* bdev = map_bh->b_dev
* physical = map_bh->b_blocknr
* nblocks = map_bh->b_size (no of logical blocks in extent)
* compress_count = map_bh->b_private
* first_logical_block
*/
if (get_block(inode, block_in_file, map_bh, 0)) //BLOCK_MAPPER
goto confused;
*first_logical_block = block_in_file;
}
/* generally is mapped.. so FALSE */
if (!buffer_mapped(map_bh)) {
fully_mapped = 0;
if (first_hole == blocks_per_page)
first_hole = page_block;
page_block++;
block_in_file++;
continue;
}
/* some filesystems will copy data into the page during
* the get_block call, in which case we don't want to
* read it again. map_buffer_to_page copies the data
* we just collected from get_block into the page's buffers
* so readpage doesn't have to repeat the get_block call
*/
//NEXT 3 => FALSE
if (buffer_uptodate(map_bh)) {
printk("\nIn map_buffer_to_page()");
map_buffer_to_page(page, map_bh, page_block);
goto confused;
}
if (first_hole != blocks_per_page)
goto confused; /* hole -> non-hole */
/* Contiguous blocks? */
if (page_block && blocks[page_block-1] != map_bh->b_blocknr-1)
goto confused;
nblocks = map_bh->b_size >> blkbits;
printk(KERN_INFO "\nnblocks_mapped : %u", nblocks);
//MAIN PART
if (!*cb) {
*cb = kzalloc(sizeof(struct compressed_bio), GFP_NOFS);
if (!*cb) {
/* ERROR */
BUG_ON(1);
err = -ENOMEM;
}
err = compressed_bio_init(*cb, inode, *first_logical_block, *(unsigned *)map_bh->b_private,
nblocks << PAGE_CACHE_SHIFT, 0);//compressed_len = 0
if (err) {
/* ERROR = -ENOMEM */
err = -ENOMEM;
}
kfree((unsigned *)map_bh->b_private);
map_bh->b_private = NULL;
}
for (relative_block = 0; ; relative_block++) {
if (relative_block == nblocks) {
clear_buffer_mapped(map_bh);
break;
} else if (page_block == blocks_per_page)
break;
blocks[page_block] = map_bh->b_blocknr+relative_block;
page_block++;
block_in_file++;
}
bdev = map_bh->b_bdev;
}
if (first_hole != blocks_per_page) {
zero_user_segment(page, first_hole << blkbits, PAGE_CACHE_SIZE);
if (first_hole == 0) {
SetPageUptodate(page);
unlock_page(page);
goto out;
}
} else if (fully_mapped) {
//TRUE...REQ?
SetPageMappedToDisk(page);
}
if (fully_mapped && blocks_per_page == 1 && !PageUptodate(page) &&
cleancache_get_page(page) == 0) {
//FALSE
printk(KERN_INFO "\nSet_Page_Uptodate");
SetPageUptodate(page);
goto confused;
}
/*
* This page will go to BIO. Do we need to send this BIO off first?
*/
/* if (bio && (*last_block_in_bio != blocks[0] - 1)) */
/* bio = mpage_bio_submit(READ, bio); */
/* alloc_new: */
/* if (bio == NULL) { */
/* bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9), */
/* min_t(int, nr_pages, bio_get_nr_vecs(bdev)), */
/* GFP_KERNEL); */
/* if (bio == NULL) */
/* goto confused; */
/* } */
/* length = first_hole << blkbits; */
/* if (bio_add_page(bio, page, length, 0) < length) { */
/* bio = mpage_bio_submit(READ, bio); */
/* goto alloc_new; */
/* } */
/* relative_block = block_in_file - *first_logical_block; */
/* nblocks = map_bh->b_size >> blkbits; */
/* if ((buffer_boundary(map_bh) && relative_block == nblocks) || */
/* (first_hole != blocks_per_page)) */
/* bio = mpage_bio_submit(READ, bio); */
/* else */
/* *last_block_in_bio = blocks[blocks_per_page - 1]; */
out:
return bio;
confused:
printk(KERN_INFO "\nCONFUSED !");
if (bio)
bio = mpage_bio_submit(READ, bio);
if (!PageUptodate(page))
block_read_full_page(page, get_block);
else
unlock_page(page);
goto out;
}
