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Go Back   Linux Archive > Redhat > Cluster Development

 
 
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Old 03-11-2011, 09:09 AM
Steven Whitehouse
 
Default GFS2: fix block allocation check for fallocate

Hi,

On Fri, 2011-03-11 at 00:49 -0600, Benjamin Marzinski wrote:
> GFS2 fallocate wasn't properly checking if a blocks were already allocated.
> In write_empty_blocks(), if a page didn't have buffer_heads attached, GFS2
> was always treating it as if there were no blocks allocated for that page.
> GFS2 now calls gfs2_block_map() to check if the blocks are allocated before
> writing them out.
>
> Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
> ---
> fs/gfs2/file.c | 56 +++++++++++++++++++++++++++++++-------------------------
> 1 file changed, 31 insertions(+), 25 deletions(-)
>
Thanks for the patch. Now in the -nmw git tree,

Steve.

> Index: gfs2-2.6-nmw/fs/gfs2/file.c
> ================================================== =================
> --- gfs2-2.6-nmw.orig/fs/gfs2/file.c
> +++ gfs2-2.6-nmw/fs/gfs2/file.c
> @@ -622,8 +622,7 @@ static void empty_write_end(struct page
> {
> struct gfs2_inode *ip = GFS2_I(page->mapping->host);
>
> - page_zero_new_buffers(page, from, to);
> - flush_dcache_page(page);
> + zero_user(page, from, to-from);
> mark_page_accessed(page);
>
> if (!gfs2_is_writeback(ip))
> @@ -632,36 +631,43 @@ static void empty_write_end(struct page
> block_commit_write(page, from, to);
> }
>
> -static int write_empty_blocks(struct page *page, unsigned from, unsigned to)
> +static int needs_empty_write(sector_t block, struct inode *inode)
> {
> - unsigned start, end, next;
> - struct buffer_head *bh, *head;
> int error;
> + struct buffer_head bh_map = { .b_state = 0, .b_blocknr = 0 };
>
> - if (!page_has_buffers(page)) {
> - error = __block_write_begin(page, from, to - from, gfs2_block_map);
> - if (unlikely(error))
> - return error;
> + bh_map.b_size = 1 << inode->i_blkbits;
> + error = gfs2_block_map(inode, block, &bh_map, 0);
> + if (unlikely(error))
> + return error;
> + return !buffer_mapped(&bh_map);
> +}
>
> - empty_write_end(page, from, to);
> - return 0;
> - }
> +static int write_empty_blocks(struct page *page, unsigned from, unsigned to)
> +{
> + struct inode *inode = page->mapping->host;
> + unsigned start, end, next, blksize;
> + sector_t block = page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
> + int ret;
>
> - bh = head = page_buffers(page);
> + blksize = 1 << inode->i_blkbits;
> next = end = 0;
> while (next < from) {
> - next += bh->b_size;
> - bh = bh->b_this_page;
> + next += blksize;
> + block++;
> }
> start = next;
> do {
> - next += bh->b_size;
> - if (buffer_mapped(bh)) {
> + next += blksize;
> + ret = needs_empty_write(block, inode);
> + if (unlikely(ret < 0))
> + return ret;
> + if (ret == 0) {
> if (end) {
> - error = __block_write_begin(page, start, end - start,
> - gfs2_block_map);
> - if (unlikely(error))
> - return error;
> + ret = __block_write_begin(page, start, end - start,
> + gfs2_block_map);
> + if (unlikely(ret))
> + return ret;
> empty_write_end(page, start, end);
> end = 0;
> }
> @@ -669,13 +675,13 @@ static int write_empty_blocks(struct pag
> }
> else
> end = next;
> - bh = bh->b_this_page;
> + block++;
> } while (next < to);
>
> if (end) {
> - error = __block_write_begin(page, start, end - start, gfs2_block_map);
> - if (unlikely(error))
> - return error;
> + ret = __block_write_begin(page, start, end - start, gfs2_block_map);
> + if (unlikely(ret))
> + return ret;
> empty_write_end(page, start, end);
> }
>
>
 

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