fs: restore nobh
Implement nobh in new aops. This is a bit tricky. FWIW, nobh_truncate is now implemented in a way that does not create blocks in sparse regions, which is a silly thing for it to have been doing (isn't it?) ext2 survives fsx and fsstress. jfs is converted as well... ext3 should be easy to do (but not done yet). [akpm@linux-foundation.org: coding-style fixes] Cc: Badari Pulavarty <pbadari@us.ibm.com> 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
b6af1bcd87
commit
03158cd7eb
4 changed files with 178 additions and 88 deletions
229
fs/buffer.c
229
fs/buffer.c
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@ -2369,7 +2369,7 @@ block_page_mkwrite(struct vm_area_struct *vma, struct page *page,
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}
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/*
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* nobh_prepare_write()'s prereads are special: the buffer_heads are freed
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* nobh_write_begin()'s prereads are special: the buffer_heads are freed
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* immediately, while under the page lock. So it needs a special end_io
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* handler which does not touch the bh after unlocking it.
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*/
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@ -2378,17 +2378,46 @@ static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate)
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__end_buffer_read_notouch(bh, uptodate);
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}
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/*
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* Attach the singly-linked list of buffers created by nobh_write_begin, to
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* the page (converting it to circular linked list and taking care of page
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* dirty races).
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*/
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static void attach_nobh_buffers(struct page *page, struct buffer_head *head)
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{
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struct buffer_head *bh;
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BUG_ON(!PageLocked(page));
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spin_lock(&page->mapping->private_lock);
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bh = head;
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do {
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if (PageDirty(page))
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set_buffer_dirty(bh);
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if (!bh->b_this_page)
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bh->b_this_page = head;
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bh = bh->b_this_page;
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} while (bh != head);
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attach_page_buffers(page, head);
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spin_unlock(&page->mapping->private_lock);
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}
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/*
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* On entry, the page is fully not uptodate.
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* On exit the page is fully uptodate in the areas outside (from,to)
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*/
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int nobh_prepare_write(struct page *page, unsigned from, unsigned to,
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int nobh_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)
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{
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struct inode *inode = page->mapping->host;
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struct inode *inode = mapping->host;
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const unsigned blkbits = inode->i_blkbits;
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const unsigned blocksize = 1 << blkbits;
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struct buffer_head *head, *bh;
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struct page *page;
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pgoff_t index;
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unsigned from, to;
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unsigned block_in_page;
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unsigned block_start, block_end;
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sector_t block_in_file;
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@ -2397,8 +2426,23 @@ int nobh_prepare_write(struct page *page, unsigned from, unsigned to,
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int ret = 0;
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int is_mapped_to_disk = 1;
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if (page_has_buffers(page))
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return block_prepare_write(page, from, to, get_block);
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index = pos >> PAGE_CACHE_SHIFT;
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from = pos & (PAGE_CACHE_SIZE - 1);
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to = from + len;
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page = __grab_cache_page(mapping, index);
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if (!page)
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return -ENOMEM;
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*pagep = page;
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*fsdata = NULL;
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if (page_has_buffers(page)) {
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unlock_page(page);
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page_cache_release(page);
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*pagep = NULL;
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return block_write_begin(file, mapping, pos, len, flags, pagep,
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fsdata, get_block);
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}
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if (PageMappedToDisk(page))
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return 0;
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@ -2413,8 +2457,10 @@ int nobh_prepare_write(struct page *page, unsigned from, unsigned to,
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* than the circular one we're used to.
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*/
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head = alloc_page_buffers(page, blocksize, 0);
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if (!head)
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return -ENOMEM;
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if (!head) {
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ret = -ENOMEM;
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goto out_release;
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}
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block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits);
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@ -2483,15 +2529,12 @@ int nobh_prepare_write(struct page *page, unsigned from, unsigned to,
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if (is_mapped_to_disk)
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SetPageMappedToDisk(page);
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do {
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bh = head;
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head = head->b_this_page;
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free_buffer_head(bh);
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} while (head);
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*fsdata = head; /* to be released by nobh_write_end */
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return 0;
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failed:
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BUG_ON(!ret);
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/*
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* Error recovery is a bit difficult. We need to zero out blocks that
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* were newly allocated, and dirty them to ensure they get written out.
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@ -2499,64 +2542,57 @@ int nobh_prepare_write(struct page *page, unsigned from, unsigned to,
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* the handling of potential IO errors during writeout would be hard
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* (could try doing synchronous writeout, but what if that fails too?)
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*/
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spin_lock(&page->mapping->private_lock);
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bh = head;
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block_start = 0;
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do {
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if (PageUptodate(page))
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set_buffer_uptodate(bh);
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if (PageDirty(page))
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set_buffer_dirty(bh);
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attach_nobh_buffers(page, head);
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page_zero_new_buffers(page, from, to);
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block_end = block_start+blocksize;
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if (block_end <= from)
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goto next;
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if (block_start >= to)
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goto next;
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out_release:
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unlock_page(page);
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page_cache_release(page);
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*pagep = NULL;
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if (buffer_new(bh)) {
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clear_buffer_new(bh);
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if (!buffer_uptodate(bh)) {
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zero_user_page(page, block_start, bh->b_size, KM_USER0);
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set_buffer_uptodate(bh);
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}
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mark_buffer_dirty(bh);
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}
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next:
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block_start = block_end;
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if (!bh->b_this_page)
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bh->b_this_page = head;
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bh = bh->b_this_page;
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} while (bh != head);
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attach_page_buffers(page, head);
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spin_unlock(&page->mapping->private_lock);
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if (pos + len > inode->i_size)
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vmtruncate(inode, inode->i_size);
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return ret;
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}
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EXPORT_SYMBOL(nobh_prepare_write);
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EXPORT_SYMBOL(nobh_write_begin);
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/*
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* Make sure any changes to nobh_commit_write() are reflected in
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* nobh_truncate_page(), since it doesn't call commit_write().
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*/
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int nobh_commit_write(struct file *file, struct page *page,
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unsigned from, unsigned to)
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int nobh_write_end(struct file *file, struct address_space *mapping,
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loff_t pos, unsigned len, unsigned copied,
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struct page *page, void *fsdata)
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{
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struct inode *inode = page->mapping->host;
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loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
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struct buffer_head *head = NULL;
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struct buffer_head *bh;
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if (page_has_buffers(page))
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return generic_commit_write(file, page, from, to);
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if (!PageMappedToDisk(page)) {
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if (unlikely(copied < len) && !page_has_buffers(page))
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attach_nobh_buffers(page, head);
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if (page_has_buffers(page))
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return generic_write_end(file, mapping, pos, len,
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copied, page, fsdata);
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}
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SetPageUptodate(page);
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set_page_dirty(page);
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if (pos > inode->i_size) {
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i_size_write(inode, pos);
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if (pos+copied > inode->i_size) {
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i_size_write(inode, pos+copied);
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mark_inode_dirty(inode);
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}
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return 0;
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unlock_page(page);
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page_cache_release(page);
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head = fsdata;
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while (head) {
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bh = head;
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head = head->b_this_page;
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free_buffer_head(bh);
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}
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return copied;
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}
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EXPORT_SYMBOL(nobh_commit_write);
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EXPORT_SYMBOL(nobh_write_end);
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/*
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* nobh_writepage() - based on block_full_write_page() except
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@ -2609,44 +2645,79 @@ int nobh_writepage(struct page *page, get_block_t *get_block,
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}
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EXPORT_SYMBOL(nobh_writepage);
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/*
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* This function assumes that ->prepare_write() uses nobh_prepare_write().
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*/
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int nobh_truncate_page(struct address_space *mapping, loff_t from)
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int nobh_truncate_page(struct address_space *mapping,
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loff_t from, get_block_t *get_block)
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{
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struct inode *inode = mapping->host;
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unsigned blocksize = 1 << inode->i_blkbits;
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pgoff_t index = from >> PAGE_CACHE_SHIFT;
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unsigned offset = from & (PAGE_CACHE_SIZE-1);
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unsigned to;
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unsigned blocksize;
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sector_t iblock;
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unsigned length, pos;
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struct inode *inode = mapping->host;
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struct page *page;
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const struct address_space_operations *a_ops = mapping->a_ops;
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int ret = 0;
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struct buffer_head map_bh;
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int err;
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if ((offset & (blocksize - 1)) == 0)
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goto out;
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blocksize = 1 << inode->i_blkbits;
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length = offset & (blocksize - 1);
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/* Block boundary? Nothing to do */
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if (!length)
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return 0;
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length = blocksize - length;
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iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
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ret = -ENOMEM;
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page = grab_cache_page(mapping, index);
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err = -ENOMEM;
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if (!page)
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goto out;
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to = (offset + blocksize) & ~(blocksize - 1);
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ret = a_ops->prepare_write(NULL, page, offset, to);
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if (ret == 0) {
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zero_user_page(page, offset, PAGE_CACHE_SIZE - offset,
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KM_USER0);
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/*
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* It would be more correct to call aops->commit_write()
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* here, but this is more efficient.
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*/
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SetPageUptodate(page);
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set_page_dirty(page);
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if (page_has_buffers(page)) {
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has_buffers:
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unlock_page(page);
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page_cache_release(page);
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return block_truncate_page(mapping, from, get_block);
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}
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/* Find the buffer that contains "offset" */
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pos = blocksize;
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while (offset >= pos) {
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iblock++;
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pos += blocksize;
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}
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err = get_block(inode, iblock, &map_bh, 0);
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if (err)
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goto unlock;
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/* unmapped? It's a hole - nothing to do */
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if (!buffer_mapped(&map_bh))
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goto unlock;
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/* Ok, it's mapped. Make sure it's up-to-date */
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if (!PageUptodate(page)) {
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err = mapping->a_ops->readpage(NULL, page);
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if (err) {
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page_cache_release(page);
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goto out;
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}
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lock_page(page);
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if (!PageUptodate(page)) {
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err = -EIO;
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goto unlock;
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}
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if (page_has_buffers(page))
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goto has_buffers;
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}
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zero_user_page(page, offset, length, KM_USER0);
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set_page_dirty(page);
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err = 0;
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unlock:
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unlock_page(page);
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page_cache_release(page);
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out:
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return ret;
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return err;
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}
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EXPORT_SYMBOL(nobh_truncate_page);
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@ -659,6 +659,20 @@ ext2_write_begin(struct file *file, struct address_space *mapping,
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return __ext2_write_begin(file, mapping, pos, len, flags, pagep,fsdata);
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}
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static int
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ext2_nobh_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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{
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/*
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* Dir-in-pagecache still uses ext2_write_begin. Would have to rework
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* directory handling code to pass around offsets rather than struct
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* pages in order to make this work easily.
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*/
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return nobh_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
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ext2_get_block);
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}
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static int ext2_nobh_writepage(struct page *page,
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struct writeback_control *wbc)
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{
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@ -710,7 +724,8 @@ const struct address_space_operations ext2_nobh_aops = {
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.readpages = ext2_readpages,
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.writepage = ext2_nobh_writepage,
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.sync_page = block_sync_page,
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/* XXX: todo */
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.write_begin = ext2_nobh_write_begin,
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.write_end = nobh_write_end,
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.bmap = ext2_bmap,
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.direct_IO = ext2_direct_IO,
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.writepages = ext2_writepages,
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@ -927,7 +942,8 @@ void ext2_truncate (struct inode * inode)
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if (mapping_is_xip(inode->i_mapping))
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xip_truncate_page(inode->i_mapping, inode->i_size);
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else if (test_opt(inode->i_sb, NOBH))
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nobh_truncate_page(inode->i_mapping, inode->i_size);
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nobh_truncate_page(inode->i_mapping,
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inode->i_size, ext2_get_block);
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else
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block_truncate_page(inode->i_mapping,
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inode->i_size, ext2_get_block);
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@ -279,8 +279,7 @@ static int jfs_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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{
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*pagep = NULL;
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return block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
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return nobh_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
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jfs_get_block);
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}
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@ -306,7 +305,7 @@ const struct address_space_operations jfs_aops = {
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.writepages = jfs_writepages,
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.sync_page = block_sync_page,
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.write_begin = jfs_write_begin,
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.write_end = generic_write_end,
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.write_end = nobh_write_end,
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.bmap = jfs_bmap,
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.direct_IO = jfs_direct_IO,
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};
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@ -359,7 +358,7 @@ void jfs_truncate(struct inode *ip)
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{
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jfs_info("jfs_truncate: size = 0x%lx", (ulong) ip->i_size);
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block_truncate_page(ip->i_mapping, ip->i_size, jfs_get_block);
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nobh_truncate_page(ip->i_mapping, ip->i_size, jfs_get_block);
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IWRITE_LOCK(ip, RDWRLOCK_NORMAL);
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jfs_truncate_nolock(ip, ip->i_size);
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@ -226,9 +226,13 @@ sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
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int generic_commit_write(struct file *, struct page *, unsigned, unsigned);
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int block_truncate_page(struct address_space *, loff_t, get_block_t *);
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int file_fsync(struct file *, struct dentry *, int);
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int nobh_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
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int nobh_commit_write(struct file *, struct page *, unsigned, unsigned);
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int nobh_truncate_page(struct address_space *, loff_t);
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int nobh_write_begin(struct file *, struct address_space *,
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loff_t, unsigned, unsigned,
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struct page **, void **, get_block_t*);
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int nobh_write_end(struct file *, struct address_space *,
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loff_t, unsigned, unsigned,
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struct page *, void *);
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int nobh_truncate_page(struct address_space *, loff_t, get_block_t *);
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int nobh_writepage(struct page *page, get_block_t *get_block,
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struct writeback_control *wbc);
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