fs: new cont helpers
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
Linus Torvalds
parent
7765ec26ae
commit
89e107877b
202
fs/buffer.c
202
fs/buffer.c
@ -2156,14 +2156,14 @@ int block_read_full_page(struct page *page, get_block_t *get_block)
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}
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/* utility function for filesystems that need to do work on expanding
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* truncates. Uses prepare/commit_write to allow the filesystem to
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* truncates. Uses filesystem pagecache writes to allow the filesystem to
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* deal with the hole.
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*/
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static int __generic_cont_expand(struct inode *inode, loff_t size,
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pgoff_t index, unsigned int offset)
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int generic_cont_expand_simple(struct inode *inode, loff_t size)
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{
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struct address_space *mapping = inode->i_mapping;
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struct page *page;
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void *fsdata;
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unsigned long limit;
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int err;
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@ -2176,140 +2176,134 @@ static int __generic_cont_expand(struct inode *inode, loff_t size,
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if (size > inode->i_sb->s_maxbytes)
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goto out;
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err = -ENOMEM;
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page = grab_cache_page(mapping, index);
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if (!page)
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err = pagecache_write_begin(NULL, mapping, size, 0,
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AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND,
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&page, &fsdata);
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if (err)
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goto out;
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err = mapping->a_ops->prepare_write(NULL, page, offset, offset);
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if (err) {
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/*
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* ->prepare_write() may have instantiated a few blocks
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* outside i_size. Trim these off again.
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*/
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unlock_page(page);
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page_cache_release(page);
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vmtruncate(inode, inode->i_size);
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goto out;
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}
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err = mapping->a_ops->commit_write(NULL, page, offset, offset);
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err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata);
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BUG_ON(err > 0);
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unlock_page(page);
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page_cache_release(page);
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if (err > 0)
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err = 0;
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out:
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return err;
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}
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int generic_cont_expand(struct inode *inode, loff_t size)
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{
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pgoff_t index;
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unsigned int offset;
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offset = (size & (PAGE_CACHE_SIZE - 1)); /* Within page */
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/* ugh. in prepare/commit_write, if from==to==start of block, we
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** skip the prepare. make sure we never send an offset for the start
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** of a block
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*/
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* skip the prepare. make sure we never send an offset for the start
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* of a block.
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* XXX: actually, this should be handled in those filesystems by
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* checking for the AOP_FLAG_CONT_EXPAND flag.
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*/
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if ((offset & (inode->i_sb->s_blocksize - 1)) == 0) {
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/* caller must handle this extra byte. */
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offset++;
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size++;
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}
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index = size >> PAGE_CACHE_SHIFT;
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return __generic_cont_expand(inode, size, index, offset);
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return generic_cont_expand_simple(inode, size);
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}
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int generic_cont_expand_simple(struct inode *inode, loff_t size)
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int cont_expand_zero(struct file *file, struct address_space *mapping,
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loff_t pos, loff_t *bytes)
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{
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loff_t pos = size - 1;
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pgoff_t index = pos >> PAGE_CACHE_SHIFT;
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unsigned int offset = (pos & (PAGE_CACHE_SIZE - 1)) + 1;
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struct inode *inode = mapping->host;
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unsigned blocksize = 1 << inode->i_blkbits;
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struct page *page;
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void *fsdata;
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pgoff_t index, curidx;
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loff_t curpos;
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unsigned zerofrom, offset, len;
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int err = 0;
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/* prepare/commit_write can handle even if from==to==start of block. */
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return __generic_cont_expand(inode, size, index, offset);
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index = pos >> PAGE_CACHE_SHIFT;
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offset = pos & ~PAGE_CACHE_MASK;
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while (index > (curidx = (curpos = *bytes)>>PAGE_CACHE_SHIFT)) {
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zerofrom = curpos & ~PAGE_CACHE_MASK;
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if (zerofrom & (blocksize-1)) {
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*bytes |= (blocksize-1);
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(*bytes)++;
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}
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len = PAGE_CACHE_SIZE - zerofrom;
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err = pagecache_write_begin(file, mapping, curpos, len,
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AOP_FLAG_UNINTERRUPTIBLE,
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&page, &fsdata);
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if (err)
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goto out;
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zero_user_page(page, zerofrom, len, KM_USER0);
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err = pagecache_write_end(file, mapping, curpos, len, len,
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page, fsdata);
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if (err < 0)
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goto out;
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BUG_ON(err != len);
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err = 0;
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}
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/* page covers the boundary, find the boundary offset */
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if (index == curidx) {
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zerofrom = curpos & ~PAGE_CACHE_MASK;
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/* if we will expand the thing last block will be filled */
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if (offset <= zerofrom) {
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goto out;
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}
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if (zerofrom & (blocksize-1)) {
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*bytes |= (blocksize-1);
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(*bytes)++;
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}
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len = offset - zerofrom;
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err = pagecache_write_begin(file, mapping, curpos, len,
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AOP_FLAG_UNINTERRUPTIBLE,
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&page, &fsdata);
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if (err)
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goto out;
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zero_user_page(page, zerofrom, len, KM_USER0);
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err = pagecache_write_end(file, mapping, curpos, len, len,
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page, fsdata);
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if (err < 0)
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goto out;
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BUG_ON(err != len);
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err = 0;
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}
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out:
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return err;
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}
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/*
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* For moronic filesystems that do not allow holes in file.
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* We may have to extend the file.
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*/
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int cont_prepare_write(struct page *page, unsigned offset,
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unsigned to, get_block_t *get_block, loff_t *bytes)
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int cont_write_begin(struct file *file, struct address_space *mapping,
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loff_t pos, unsigned len, unsigned flags,
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struct page **pagep, void **fsdata,
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get_block_t *get_block, loff_t *bytes)
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{
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struct address_space *mapping = page->mapping;
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struct inode *inode = mapping->host;
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struct page *new_page;
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pgoff_t pgpos;
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long status;
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unsigned zerofrom;
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unsigned blocksize = 1 << inode->i_blkbits;
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unsigned zerofrom;
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int err;
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while(page->index > (pgpos = *bytes>>PAGE_CACHE_SHIFT)) {
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status = -ENOMEM;
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new_page = grab_cache_page(mapping, pgpos);
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if (!new_page)
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goto out;
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/* we might sleep */
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if (*bytes>>PAGE_CACHE_SHIFT != pgpos) {
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unlock_page(new_page);
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page_cache_release(new_page);
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continue;
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}
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zerofrom = *bytes & ~PAGE_CACHE_MASK;
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if (zerofrom & (blocksize-1)) {
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*bytes |= (blocksize-1);
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(*bytes)++;
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}
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status = __block_prepare_write(inode, new_page, zerofrom,
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PAGE_CACHE_SIZE, get_block);
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if (status)
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goto out_unmap;
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zero_user_page(new_page, zerofrom, PAGE_CACHE_SIZE - zerofrom,
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KM_USER0);
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generic_commit_write(NULL, new_page, zerofrom, PAGE_CACHE_SIZE);
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unlock_page(new_page);
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page_cache_release(new_page);
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err = cont_expand_zero(file, mapping, pos, bytes);
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if (err)
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goto out;
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zerofrom = *bytes & ~PAGE_CACHE_MASK;
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if (pos+len > *bytes && zerofrom & (blocksize-1)) {
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*bytes |= (blocksize-1);
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(*bytes)++;
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}
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if (page->index < pgpos) {
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/* completely inside the area */
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zerofrom = offset;
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} else {
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/* page covers the boundary, find the boundary offset */
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zerofrom = *bytes & ~PAGE_CACHE_MASK;
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/* if we will expand the thing last block will be filled */
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if (to > zerofrom && (zerofrom & (blocksize-1))) {
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*bytes |= (blocksize-1);
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(*bytes)++;
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}
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/* starting below the boundary? Nothing to zero out */
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if (offset <= zerofrom)
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zerofrom = offset;
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}
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status = __block_prepare_write(inode, page, zerofrom, to, get_block);
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if (status)
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goto out1;
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if (zerofrom < offset) {
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zero_user_page(page, zerofrom, offset - zerofrom, KM_USER0);
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__block_commit_write(inode, page, zerofrom, offset);
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}
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return 0;
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out1:
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ClearPageUptodate(page);
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return status;
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out_unmap:
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ClearPageUptodate(new_page);
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unlock_page(new_page);
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page_cache_release(new_page);
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*pagep = NULL;
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err = block_write_begin(file, mapping, pos, len,
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flags, pagep, fsdata, get_block);
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out:
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return status;
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return err;
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}
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int block_prepare_write(struct page *page, unsigned from, unsigned to,
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@ -3191,7 +3185,7 @@ EXPORT_SYMBOL(block_read_full_page);
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EXPORT_SYMBOL(block_sync_page);
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EXPORT_SYMBOL(block_truncate_page);
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EXPORT_SYMBOL(block_write_full_page);
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EXPORT_SYMBOL(cont_prepare_write);
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EXPORT_SYMBOL(cont_write_begin);
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EXPORT_SYMBOL(end_buffer_read_sync);
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EXPORT_SYMBOL(end_buffer_write_sync);
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EXPORT_SYMBOL(file_fsync);
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@ -214,8 +214,9 @@ int generic_write_end(struct file *, struct address_space *,
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struct page *, void *);
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void page_zero_new_buffers(struct page *page, unsigned from, unsigned to);
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int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
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int cont_prepare_write(struct page*, unsigned, unsigned, get_block_t*,
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loff_t *);
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int cont_write_begin(struct file *, struct address_space *, loff_t,
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unsigned, unsigned, struct page **, void **,
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get_block_t *, loff_t *);
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int generic_cont_expand(struct inode *inode, loff_t size);
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int generic_cont_expand_simple(struct inode *inode, loff_t size);
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int block_commit_write(struct page *page, unsigned from, unsigned to);
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@ -395,6 +395,7 @@ enum positive_aop_returns {
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};
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#define AOP_FLAG_UNINTERRUPTIBLE 0x0001 /* will not do a short write */
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#define AOP_FLAG_CONT_EXPAND 0x0002 /* called from cont_expand */
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/*
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* oh the beauties of C type declarations.
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@ -1684,6 +1684,7 @@ size_t iov_iter_copy_from_user_atomic(struct page *page,
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return copied;
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}
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EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
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/*
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* This has the same sideeffects and return value as
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@ -1710,6 +1711,7 @@ size_t iov_iter_copy_from_user(struct page *page,
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kunmap(page);
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return copied;
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}
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EXPORT_SYMBOL(iov_iter_copy_from_user);
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static void __iov_iter_advance_iov(struct iov_iter *i, size_t bytes)
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{
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@ -1741,6 +1743,7 @@ void iov_iter_advance(struct iov_iter *i, size_t bytes)
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__iov_iter_advance_iov(i, bytes);
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i->count -= bytes;
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}
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EXPORT_SYMBOL(iov_iter_advance);
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/*
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* Fault in the first iovec of the given iov_iter, to a maximum length
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@ -1757,6 +1760,7 @@ int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
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bytes = min(bytes, i->iov->iov_len - i->iov_offset);
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return fault_in_pages_readable(buf, bytes);
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}
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EXPORT_SYMBOL(iov_iter_fault_in_readable);
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/*
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* Return the count of just the current iov_iter segment.
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@ -1769,6 +1773,7 @@ size_t iov_iter_single_seg_count(struct iov_iter *i)
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else
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return min(i->count, iov->iov_len - i->iov_offset);
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}
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EXPORT_SYMBOL(iov_iter_single_seg_count);
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/*
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* Performs necessary checks before doing a write
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