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fs: new cont helpers

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Rework the generic block "cont" routines to handle the new aops.  Supporting
cont_prepare_write would take quite a lot of code to support, so remove it
instead (and we later convert all filesystems to use it).

write_begin gets passed AOP_FLAG_CONT_EXPAND when called from
generic_cont_expand, so filesystems can avoid the old hacks they used.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Nick Piggin 2007-10-16 01:25:07 -07:00 committed by Linus Torvalds
parent 7765ec26ae
commit 89e107877b
4 changed files with 107 additions and 106 deletions
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202
fs/buffer.c
View file

@ -2156,14 +2156,14 @@ int block_read_full_page(struct page *page, get_block_t *get_block)
}
/* utility function for filesystems that need to do work on expanding
* truncates. Uses prepare/commit_write to allow the filesystem to
* truncates. Uses filesystem pagecache writes to allow the filesystem to
* deal with the hole.
*/
static int __generic_cont_expand(struct inode *inode, loff_t size,
pgoff_t index, unsigned int offset)
int generic_cont_expand_simple(struct inode *inode, loff_t size)
{
struct address_space *mapping = inode->i_mapping;
struct page *page;
void *fsdata;
unsigned long limit;
int err;
@ -2176,140 +2176,134 @@ static int __generic_cont_expand(struct inode *inode, loff_t size,
if (size > inode->i_sb->s_maxbytes)
goto out;
err = -ENOMEM;
page = grab_cache_page(mapping, index);
if (!page)
err = pagecache_write_begin(NULL, mapping, size, 0,
AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND,
&page, &fsdata);
if (err)
goto out;
err = mapping->a_ops->prepare_write(NULL, page, offset, offset);
if (err) {
/*
* ->prepare_write() may have instantiated a few blocks
* outside i_size. Trim these off again.
*/
unlock_page(page);
page_cache_release(page);
vmtruncate(inode, inode->i_size);
goto out;
}
err = mapping->a_ops->commit_write(NULL, page, offset, offset);
err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata);
BUG_ON(err > 0);
unlock_page(page);
page_cache_release(page);
if (err > 0)
err = 0;
out:
return err;
}
int generic_cont_expand(struct inode *inode, loff_t size)
{
pgoff_t index;
unsigned int offset;
offset = (size & (PAGE_CACHE_SIZE - 1)); /* Within page */
/* ugh. in prepare/commit_write, if from==to==start of block, we
** skip the prepare. make sure we never send an offset for the start
** of a block
*/
* skip the prepare. make sure we never send an offset for the start
* of a block.
* XXX: actually, this should be handled in those filesystems by
* checking for the AOP_FLAG_CONT_EXPAND flag.
*/
if ((offset & (inode->i_sb->s_blocksize - 1)) == 0) {
/* caller must handle this extra byte. */
offset++;
size++;
}
index = size >> PAGE_CACHE_SHIFT;
return __generic_cont_expand(inode, size, index, offset);
return generic_cont_expand_simple(inode, size);
}
int generic_cont_expand_simple(struct inode *inode, loff_t size)
int cont_expand_zero(struct file *file, struct address_space *mapping,
loff_t pos, loff_t *bytes)
{
loff_t pos = size - 1;
pgoff_t index = pos >> PAGE_CACHE_SHIFT;
unsigned int offset = (pos & (PAGE_CACHE_SIZE - 1)) + 1;
struct inode *inode = mapping->host;
unsigned blocksize = 1 << inode->i_blkbits;
struct page *page;
void *fsdata;
pgoff_t index, curidx;
loff_t curpos;
unsigned zerofrom, offset, len;
int err = 0;
/* prepare/commit_write can handle even if from==to==start of block. */
return __generic_cont_expand(inode, size, index, offset);
index = pos >> PAGE_CACHE_SHIFT;
offset = pos & ~PAGE_CACHE_MASK;
while (index > (curidx = (curpos = *bytes)>>PAGE_CACHE_SHIFT)) {
zerofrom = curpos & ~PAGE_CACHE_MASK;
if (zerofrom & (blocksize-1)) {
*bytes |= (blocksize-1);
(*bytes)++;
}
len = PAGE_CACHE_SIZE - zerofrom;
err = pagecache_write_begin(file, mapping, curpos, len,
AOP_FLAG_UNINTERRUPTIBLE,
&page, &fsdata);
if (err)
goto out;
zero_user_page(page, zerofrom, len, KM_USER0);
err = pagecache_write_end(file, mapping, curpos, len, len,
page, fsdata);
if (err < 0)
goto out;
BUG_ON(err != len);
err = 0;
}
/* page covers the boundary, find the boundary offset */
if (index == curidx) {
zerofrom = curpos & ~PAGE_CACHE_MASK;
/* if we will expand the thing last block will be filled */
if (offset <= zerofrom) {
goto out;
}
if (zerofrom & (blocksize-1)) {
*bytes |= (blocksize-1);
(*bytes)++;
}
len = offset - zerofrom;
err = pagecache_write_begin(file, mapping, curpos, len,
AOP_FLAG_UNINTERRUPTIBLE,
&page, &fsdata);
if (err)
goto out;
zero_user_page(page, zerofrom, len, KM_USER0);
err = pagecache_write_end(file, mapping, curpos, len, len,
page, fsdata);
if (err < 0)
goto out;
BUG_ON(err != len);
err = 0;
}
out:
return err;
}
/*
* For moronic filesystems that do not allow holes in file.
* We may have to extend the file.
*/
int cont_prepare_write(struct page *page, unsigned offset,
unsigned to, get_block_t *get_block, loff_t *bytes)
int cont_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata,
get_block_t *get_block, loff_t *bytes)
{
struct address_space *mapping = page->mapping;
struct inode *inode = mapping->host;
struct page *new_page;
pgoff_t pgpos;
long status;
unsigned zerofrom;
unsigned blocksize = 1 << inode->i_blkbits;
unsigned zerofrom;
int err;
while(page->index > (pgpos = *bytes>>PAGE_CACHE_SHIFT)) {
status = -ENOMEM;
new_page = grab_cache_page(mapping, pgpos);
if (!new_page)
goto out;
/* we might sleep */
if (*bytes>>PAGE_CACHE_SHIFT != pgpos) {
unlock_page(new_page);
page_cache_release(new_page);
continue;
}
zerofrom = *bytes & ~PAGE_CACHE_MASK;
if (zerofrom & (blocksize-1)) {
*bytes |= (blocksize-1);
(*bytes)++;
}
status = __block_prepare_write(inode, new_page, zerofrom,
PAGE_CACHE_SIZE, get_block);
if (status)
goto out_unmap;
zero_user_page(new_page, zerofrom, PAGE_CACHE_SIZE - zerofrom,
KM_USER0);
generic_commit_write(NULL, new_page, zerofrom, PAGE_CACHE_SIZE);
unlock_page(new_page);
page_cache_release(new_page);
err = cont_expand_zero(file, mapping, pos, bytes);
if (err)
goto out;
zerofrom = *bytes & ~PAGE_CACHE_MASK;
if (pos+len > *bytes && zerofrom & (blocksize-1)) {
*bytes |= (blocksize-1);
(*bytes)++;
}
if (page->index < pgpos) {
/* completely inside the area */
zerofrom = offset;
} else {
/* page covers the boundary, find the boundary offset */
zerofrom = *bytes & ~PAGE_CACHE_MASK;
/* if we will expand the thing last block will be filled */
if (to > zerofrom && (zerofrom & (blocksize-1))) {
*bytes |= (blocksize-1);
(*bytes)++;
}
/* starting below the boundary? Nothing to zero out */
if (offset <= zerofrom)
zerofrom = offset;
}
status = __block_prepare_write(inode, page, zerofrom, to, get_block);
if (status)
goto out1;
if (zerofrom < offset) {
zero_user_page(page, zerofrom, offset - zerofrom, KM_USER0);
__block_commit_write(inode, page, zerofrom, offset);
}
return 0;
out1:
ClearPageUptodate(page);
return status;
out_unmap:
ClearPageUptodate(new_page);
unlock_page(new_page);
page_cache_release(new_page);
*pagep = NULL;
err = block_write_begin(file, mapping, pos, len,
flags, pagep, fsdata, get_block);
out:
return status;
return err;
}
int block_prepare_write(struct page *page, unsigned from, unsigned to,
@ -3191,7 +3185,7 @@ EXPORT_SYMBOL(block_read_full_page);
EXPORT_SYMBOL(block_sync_page);
EXPORT_SYMBOL(block_truncate_page);
EXPORT_SYMBOL(block_write_full_page);
EXPORT_SYMBOL(cont_prepare_write);
EXPORT_SYMBOL(cont_write_begin);
EXPORT_SYMBOL(end_buffer_read_sync);
EXPORT_SYMBOL(end_buffer_write_sync);
EXPORT_SYMBOL(file_fsync);

5
include/linux/buffer_head.h
View file

@ -214,8 +214,9 @@ int generic_write_end(struct file *, struct address_space *,
struct page *, void *);
void page_zero_new_buffers(struct page *page, unsigned from, unsigned to);
int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
int cont_prepare_write(struct page*, unsigned, unsigned, get_block_t*,
loff_t *);
int cont_write_begin(struct file *, struct address_space *, loff_t,
unsigned, unsigned, struct page **, void **,
get_block_t *, loff_t *);
int generic_cont_expand(struct inode *inode, loff_t size);
int generic_cont_expand_simple(struct inode *inode, loff_t size);
int block_commit_write(struct page *page, unsigned from, unsigned to);

1
include/linux/fs.h
View file

@ -395,6 +395,7 @@ enum positive_aop_returns {
};
#define AOP_FLAG_UNINTERRUPTIBLE 0x0001 /* will not do a short write */
#define AOP_FLAG_CONT_EXPAND 0x0002 /* called from cont_expand */
/*
* oh the beauties of C type declarations.

5
mm/filemap.c
View file

@ -1684,6 +1684,7 @@ size_t iov_iter_copy_from_user_atomic(struct page *page,
return copied;
}
EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
/*
* This has the same sideeffects and return value as
@ -1710,6 +1711,7 @@ size_t iov_iter_copy_from_user(struct page *page,
kunmap(page);
return copied;
}
EXPORT_SYMBOL(iov_iter_copy_from_user);
static void __iov_iter_advance_iov(struct iov_iter *i, size_t bytes)
{
@ -1741,6 +1743,7 @@ void iov_iter_advance(struct iov_iter *i, size_t bytes)
__iov_iter_advance_iov(i, bytes);
i->count -= bytes;
}
EXPORT_SYMBOL(iov_iter_advance);
/*
* Fault in the first iovec of the given iov_iter, to a maximum length
@ -1757,6 +1760,7 @@ int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
bytes = min(bytes, i->iov->iov_len - i->iov_offset);
return fault_in_pages_readable(buf, bytes);
}
EXPORT_SYMBOL(iov_iter_fault_in_readable);
/*
* Return the count of just the current iov_iter segment.
@ -1769,6 +1773,7 @@ size_t iov_iter_single_seg_count(struct iov_iter *i)
else
return min(i->count, iov->iov_len - i->iov_offset);
}
EXPORT_SYMBOL(iov_iter_single_seg_count);
/*
* Performs necessary checks before doing a write