Revert "ext4: remove no longer used functions in inode.c"
This reverts commit ccb4d7af91
.
This commit reintroduces functions ext4_block_truncate_page() and
ext4_block_zero_page_range() which has been previously removed in favour
of ext4_discard_partial_page_buffers().
In future commits we want to reintroduce those function and remove
ext4_discard_partial_page_buffers() since it is duplicating some code
and also partially duplicating work of truncate_pagecache_range(),
moreover the old implementation was much clearer.
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
parent
5a7203947a
commit
d863dc3614
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@ -2096,6 +2096,10 @@ extern int ext4_alloc_da_blocks(struct inode *inode);
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extern void ext4_set_aops(struct inode *inode);
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extern int ext4_writepage_trans_blocks(struct inode *);
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extern int ext4_chunk_trans_blocks(struct inode *, int nrblocks);
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extern int ext4_block_truncate_page(handle_t *handle,
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struct address_space *mapping, loff_t from);
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extern int ext4_block_zero_page_range(handle_t *handle,
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struct address_space *mapping, loff_t from, loff_t length);
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extern int ext4_discard_partial_page_buffers(handle_t *handle,
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struct address_space *mapping, loff_t from,
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loff_t length, int flags);
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120
fs/ext4/inode.c
120
fs/ext4/inode.c
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@ -3570,6 +3570,126 @@ next:
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return err;
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}
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/*
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* ext4_block_truncate_page() zeroes out a mapping from file offset `from'
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* up to the end of the block which corresponds to `from'.
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* This required during truncate. We need to physically zero the tail end
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* of that block so it doesn't yield old data if the file is later grown.
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*/
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int ext4_block_truncate_page(handle_t *handle,
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struct address_space *mapping, loff_t from)
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{
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unsigned offset = from & (PAGE_CACHE_SIZE-1);
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unsigned length;
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unsigned blocksize;
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struct inode *inode = mapping->host;
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blocksize = inode->i_sb->s_blocksize;
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length = blocksize - (offset & (blocksize - 1));
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return ext4_block_zero_page_range(handle, mapping, from, length);
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}
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/*
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* ext4_block_zero_page_range() zeros out a mapping of length 'length'
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* starting from file offset 'from'. The range to be zero'd must
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* be contained with in one block. If the specified range exceeds
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* the end of the block it will be shortened to end of the block
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* that cooresponds to 'from'
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*/
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int ext4_block_zero_page_range(handle_t *handle,
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struct address_space *mapping, loff_t from, loff_t length)
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{
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ext4_fsblk_t index = from >> PAGE_CACHE_SHIFT;
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unsigned offset = from & (PAGE_CACHE_SIZE-1);
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unsigned blocksize, max, pos;
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ext4_lblk_t iblock;
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struct inode *inode = mapping->host;
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struct buffer_head *bh;
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struct page *page;
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int err = 0;
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page = find_or_create_page(mapping, from >> PAGE_CACHE_SHIFT,
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mapping_gfp_mask(mapping) & ~__GFP_FS);
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if (!page)
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return -ENOMEM;
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blocksize = inode->i_sb->s_blocksize;
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max = blocksize - (offset & (blocksize - 1));
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/*
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* correct length if it does not fall between
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* 'from' and the end of the block
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*/
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if (length > max || length < 0)
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length = max;
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iblock = index << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
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if (!page_has_buffers(page))
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create_empty_buffers(page, blocksize, 0);
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/* Find the buffer that contains "offset" */
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bh = page_buffers(page);
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pos = blocksize;
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while (offset >= pos) {
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bh = bh->b_this_page;
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iblock++;
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pos += blocksize;
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}
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err = 0;
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if (buffer_freed(bh)) {
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BUFFER_TRACE(bh, "freed: skip");
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goto unlock;
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}
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if (!buffer_mapped(bh)) {
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BUFFER_TRACE(bh, "unmapped");
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ext4_get_block(inode, iblock, bh, 0);
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/* unmapped? It's a hole - nothing to do */
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if (!buffer_mapped(bh)) {
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BUFFER_TRACE(bh, "still unmapped");
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goto unlock;
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}
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}
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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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set_buffer_uptodate(bh);
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if (!buffer_uptodate(bh)) {
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err = -EIO;
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ll_rw_block(READ, 1, &bh);
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wait_on_buffer(bh);
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/* Uhhuh. Read error. Complain and punt. */
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if (!buffer_uptodate(bh))
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goto unlock;
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}
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if (ext4_should_journal_data(inode)) {
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BUFFER_TRACE(bh, "get write access");
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err = ext4_journal_get_write_access(handle, bh);
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if (err)
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goto unlock;
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}
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zero_user(page, offset, length);
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BUFFER_TRACE(bh, "zeroed end of block");
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err = 0;
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if (ext4_should_journal_data(inode)) {
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err = ext4_handle_dirty_metadata(handle, inode, bh);
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} else
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mark_buffer_dirty(bh);
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unlock:
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unlock_page(page);
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page_cache_release(page);
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return err;
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}
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int ext4_can_truncate(struct inode *inode)
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{
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if (S_ISREG(inode->i_mode))
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