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Subject[PATCH 2/4] GFS2: directly write blocks past i_size
Date
From: Benjamin Marzinski <bmarzins@redhat.com>

GFS2 was relying on the writepage code to write out the zeroed data for
fallocate. However, with FALLOC_FL_KEEP_SIZE set, this may be past i_size.
If it is, it will be ignored. To work around this, gfs2 now calls
write_dirty_buffer directly on the buffer_heads when FALLOC_FL_KEEP_SIZE
is set, and it's writing past i_size.

This version is just a cleanup of my last version

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index b2682e0..e483108 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -617,18 +617,51 @@ static ssize_t gfs2_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
return generic_file_aio_write(iocb, iov, nr_segs, pos);
}

-static void empty_write_end(struct page *page, unsigned from,
- unsigned to)
+static int empty_write_end(struct page *page, unsigned from,
+ unsigned to, int mode)
{
- struct gfs2_inode *ip = GFS2_I(page->mapping->host);
+ struct inode *inode = page->mapping->host;
+ struct gfs2_inode *ip = GFS2_I(inode);
+ struct buffer_head *bh;
+ unsigned offset, blksize = 1 << inode->i_blkbits;
+ pgoff_t end_index = i_size_read(inode) >> PAGE_CACHE_SHIFT;

zero_user(page, from, to-from);
mark_page_accessed(page);

- if (!gfs2_is_writeback(ip))
- gfs2_page_add_databufs(ip, page, from, to);
+ if (page->index < end_index || !(mode & FALLOC_FL_KEEP_SIZE)) {
+ if (!gfs2_is_writeback(ip))
+ gfs2_page_add_databufs(ip, page, from, to);
+
+ block_commit_write(page, from, to);
+ return 0;
+ }
+
+ offset = 0;
+ bh = page_buffers(page);
+ while (offset < to) {
+ if (offset >= from) {
+ set_buffer_uptodate(bh);
+ mark_buffer_dirty(bh);
+ clear_buffer_new(bh);
+ write_dirty_buffer(bh, WRITE);
+ }
+ offset += blksize;
+ bh = bh->b_this_page;
+ }

- block_commit_write(page, from, to);
+ offset = 0;
+ bh = page_buffers(page);
+ while (offset < to) {
+ if (offset >= from) {
+ wait_on_buffer(bh);
+ if (!buffer_uptodate(bh))
+ return -EIO;
+ }
+ offset += blksize;
+ bh = bh->b_this_page;
+ }
+ return 0;
}

static int needs_empty_write(sector_t block, struct inode *inode)
@@ -643,7 +676,8 @@ static int needs_empty_write(sector_t block, struct inode *inode)
return !buffer_mapped(&bh_map);
}

-static int write_empty_blocks(struct page *page, unsigned from, unsigned to)
+static int write_empty_blocks(struct page *page, unsigned from, unsigned to,
+ int mode)
{
struct inode *inode = page->mapping->host;
unsigned start, end, next, blksize;
@@ -668,7 +702,9 @@ static int write_empty_blocks(struct page *page, unsigned from, unsigned to)
gfs2_block_map);
if (unlikely(ret))
return ret;
- empty_write_end(page, start, end);
+ ret = empty_write_end(page, start, end, mode);
+ if (unlikely(ret))
+ return ret;
end = 0;
}
start = next;
@@ -682,7 +718,9 @@ static int write_empty_blocks(struct page *page, unsigned from, unsigned to)
ret = __block_write_begin(page, start, end - start, gfs2_block_map);
if (unlikely(ret))
return ret;
- empty_write_end(page, start, end);
+ ret = empty_write_end(page, start, end, mode);
+ if (unlikely(ret))
+ return ret;
}

return 0;
@@ -731,7 +769,7 @@ static int fallocate_chunk(struct inode *inode, loff_t offset, loff_t len,

if (curr == end)
to = end_offset;
- error = write_empty_blocks(page, from, to);
+ error = write_empty_blocks(page, from, to, mode);
if (!error && offset + to > inode->i_size &&
!(mode & FALLOC_FL_KEEP_SIZE)) {
i_size_write(inode, offset + to);
--
1.7.4


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