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ext4: remove unused discard_partial_page_buffers
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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>
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Lukas Czerner authored and Theodore Ts'o committed May 28, 2013
1 parent a87dd18 commit c121ffd
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Showing 2 changed files with 0 additions and 214 deletions.
8 changes: 0 additions & 8 deletions fs/ext4/ext4.h
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Original file line number Diff line number Diff line change
Expand Up @@ -580,11 +580,6 @@ enum {
#define EXT4_FREE_BLOCKS_NOFREE_FIRST_CLUSTER 0x0010
#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
*/
Expand Down Expand Up @@ -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,
Expand Down
206 changes: 0 additions & 206 deletions fs/ext4/inode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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.
Expand Down Expand Up @@ -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'.
Expand Down

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