ext4: remove unused discard_partial_page_buffers

The discard_partial_page_buffers is no longer used anywhere so we can
simply remove it including the *_no_lock variant and
EXT4_DISCARD_PARTIAL_PG_ZERO_UNMAPPED define.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

2 files changed, 0 insertions, 214 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 2d4b0aa74859..019db3c1bc3b 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -581,11 +581,6 @@ enum {
 #define EXT4_FREE_BLOCKS_NOFREE_LAST_CLUSTER    0x0020
 
 /*
- * Flags used by ext4_discard_partial_page_buffers
- */
-#define EXT4_DISCARD_PARTIAL_PG_ZERO_UNMAPPED   0x0001
-
-/*
  * ioctl commands
  */
 #define EXT4_IOC_GETFLAGS               FS_IOC_GETFLAGS
@@ -2102,9 +2097,6 @@ extern int ext4_block_zero_page_range(handle_t *handle,
                 struct address_space *mapping, loff_t from, loff_t length);
 extern int ext4_zero_partial_blocks(handle_t *handle, struct inode *inode,
                              loff_t lstart, loff_t lend);
-extern int ext4_discard_partial_page_buffers(handle_t *handle,
-                struct address_space *mapping, loff_t from,
-                loff_t length, int flags);
 extern int ext4_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf);
 extern qsize_t *ext4_get_reserved_space(struct inode *inode);
 extern void ext4_da_update_reserve_space(struct inode *inode,
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 3acf353493d4..0fca5a8c6d3e 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -136,9 +136,6 @@ static void ext4_invalidatepage(struct page *page, unsigned int offset,
                                 unsigned int length);
 static int __ext4_journalled_writepage(struct page *page, unsigned int len);
 static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh);
-static int ext4_discard_partial_page_buffers_no_lock(handle_t *handle,
-                struct inode *inode, struct page *page, loff_t from,
-                loff_t length, int flags);
 
 /*
  * Test whether an inode is a fast symlink.
@@ -3367,209 +3364,6 @@ void ext4_set_aops(struct inode *inode)
                 inode->i_mapping->a_ops = &ext4_aops;
 }
 
-
-/*
- * ext4_discard_partial_page_buffers()
- * Wrapper function for ext4_discard_partial_page_buffers_no_lock.
- * This function finds and locks the page containing the offset
- * "from" and passes it to ext4_discard_partial_page_buffers_no_lock.
- * Calling functions that already have the page locked should call
- * ext4_discard_partial_page_buffers_no_lock directly.
- */
-int ext4_discard_partial_page_buffers(handle_t *handle,
-                struct address_space *mapping, loff_t from,
-                loff_t length, int flags)
-{
-        struct inode *inode = mapping->host;
-        struct page *page;
-        int err = 0;
-
-        page = find_or_create_page(mapping, from >> PAGE_CACHE_SHIFT,
-                                   mapping_gfp_mask(mapping) & ~__GFP_FS);
-        if (!page)
-                return -ENOMEM;
-
-        err = ext4_discard_partial_page_buffers_no_lock(handle, inode, page,
-                from, length, flags);
-
-        unlock_page(page);
-        page_cache_release(page);
-        return err;
-}
-
-/*
- * ext4_discard_partial_page_buffers_no_lock()
- * Zeros a page range of length 'length' starting from offset 'from'.
- * Buffer heads that correspond to the block aligned regions of the
- * zeroed range will be unmapped.  Unblock aligned regions
- * will have the corresponding buffer head mapped if needed so that
- * that region of the page can be updated with the partial zero out.
- *
- * This function assumes that the page has already been  locked.  The
- * The range to be discarded must be contained with in the given page.
- * If the specified range exceeds the end of the page it will be shortened
- * to the end of the page that corresponds to 'from'.  This function is
- * appropriate for updating a page and it buffer heads to be unmapped and
- * zeroed for blocks that have been either released, or are going to be
- * released.
- *
- * handle: The journal handle
- * inode:  The files inode
- * page:   A locked page that contains the offset "from"
- * from:   The starting byte offset (from the beginning of the file)
- *         to begin discarding
- * len:    The length of bytes to discard
- * flags:  Optional flags that may be used:
- *
- *         EXT4_DISCARD_PARTIAL_PG_ZERO_UNMAPPED
- *         Only zero the regions of the page whose buffer heads
- *         have already been unmapped.  This flag is appropriate
- *         for updating the contents of a page whose blocks may
- *         have already been released, and we only want to zero
- *         out the regions that correspond to those released blocks.
- *
- * Returns zero on success or negative on failure.
- */
-static int ext4_discard_partial_page_buffers_no_lock(handle_t *handle,
-                struct inode *inode, struct page *page, loff_t from,
-                loff_t length, int flags)
-{
-        ext4_fsblk_t index = from >> PAGE_CACHE_SHIFT;
-        unsigned int offset = from & (PAGE_CACHE_SIZE-1);
-        unsigned int blocksize, max, pos;
-        ext4_lblk_t iblock;
-        struct buffer_head *bh;
-        int err = 0;
-
-        blocksize = inode->i_sb->s_blocksize;
-        max = PAGE_CACHE_SIZE - offset;
-
-        if (index != page->index)
-                return -EINVAL;
-
-        /*
-         * correct length if it does not fall between
-         * 'from' and the end of the page
-         */
-        if (length > max || length < 0)
-                length = max;
-
-        iblock = index << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
-
-        if (!page_has_buffers(page))
-                create_empty_buffers(page, blocksize, 0);
-
-        /* Find the buffer that contains "offset" */
-        bh = page_buffers(page);
-        pos = blocksize;
-        while (offset >= pos) {
-                bh = bh->b_this_page;
-                iblock++;
-                pos += blocksize;
-        }
-
-        pos = offset;
-        while (pos < offset + length) {
-                unsigned int end_of_block, range_to_discard;
-
-                err = 0;
-
-                /* The length of space left to zero and unmap */
-                range_to_discard = offset + length - pos;
-
-                /* The length of space until the end of the block */
-                end_of_block = blocksize - (pos & (blocksize-1));
-
-                /*
-                 * Do not unmap or zero past end of block
-                 * for this buffer head
-                 */
-                if (range_to_discard > end_of_block)
-                        range_to_discard = end_of_block;
-
-
-                /*
-                 * Skip this buffer head if we are only zeroing unampped
-                 * regions of the page
-                 */
-                if (flags & EXT4_DISCARD_PARTIAL_PG_ZERO_UNMAPPED &&
-                        buffer_mapped(bh))
-                                goto next;
-
-                /* If the range is block aligned, unmap */
-                if (range_to_discard == blocksize) {
-                        clear_buffer_dirty(bh);
-                        bh->b_bdev = NULL;
-                        clear_buffer_mapped(bh);
-                        clear_buffer_req(bh);
-                        clear_buffer_new(bh);
-                        clear_buffer_delay(bh);
-                        clear_buffer_unwritten(bh);
-                        clear_buffer_uptodate(bh);
-                        zero_user(page, pos, range_to_discard);
-                        BUFFER_TRACE(bh, "Buffer discarded");
-                        goto next;
-                }
-
-                /*
-                 * If this block is not completely contained in the range
-                 * to be discarded, then it is not going to be released. Because
-                 * we need to keep this block, we need to make sure this part
-                 * of the page is uptodate before we modify it by writeing
-                 * partial zeros on it.
-                 */
-                if (!buffer_mapped(bh)) {
-                        /*
-                         * Buffer head must be mapped before we can read
-                         * from the block
-                         */
-                        BUFFER_TRACE(bh, "unmapped");
-                        ext4_get_block(inode, iblock, bh, 0);
-                        /* unmapped? It's a hole - nothing to do */
-                        if (!buffer_mapped(bh)) {
-                                BUFFER_TRACE(bh, "still unmapped");
-                                goto next;
-                        }
-                }
-
-                /* Ok, it's mapped. Make sure it's up-to-date */
-                if (PageUptodate(page))
-                        set_buffer_uptodate(bh);
-
-                if (!buffer_uptodate(bh)) {
-                        err = -EIO;
-                        ll_rw_block(READ, 1, &bh);
-                        wait_on_buffer(bh);
-                        /* Uhhuh. Read error. Complain and punt.*/
-                        if (!buffer_uptodate(bh))
-                                goto next;
-                }
-
-                if (ext4_should_journal_data(inode)) {
-                        BUFFER_TRACE(bh, "get write access");
-                        err = ext4_journal_get_write_access(handle, bh);
-                        if (err)
-                                goto next;
-                }
-
-                zero_user(page, pos, range_to_discard);
-
-                err = 0;
-                if (ext4_should_journal_data(inode)) {
-                        err = ext4_handle_dirty_metadata(handle, inode, bh);
-                } else
-                        mark_buffer_dirty(bh);
-
-                BUFFER_TRACE(bh, "Partial buffer zeroed");
-next:
-                bh = bh->b_this_page;
-                iblock++;
-                pos += range_to_discard;
-        }
-
-        return err;
-}
-
 /*
  * ext4_block_truncate_page() zeroes out a mapping from file offset `from'
  * up to the end of the block which corresponds to `from'.