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Commit 8b421601 authored by Abhijith Das's avatar Abhijith Das Committed by Steven Whitehouse
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GFS2: BUG in gfs2_adjust_quota 



HighMem pages on i686 do not get mapped to the buffer_heads and this was
causing a NULL pointer dereference when we were trying to memset page buffers
to zero.
We now use zero_user() that kmaps the page and directly manipulates page data.
This patch also fixes a boundary condition that was incorrect.

Signed-off-by: default avatarAbhi Das <adas@redhat.com>
Signed-off-by: default avatarSteven Whitehouse <swhiteho@redhat.com>
parent b1becbde

fs/gfs2/quota.c

+3 −5
Original line number Diff line number Diff line
@@ -694,10 +694,8 @@ static int gfs2_adjust_quota(struct gfs2_inode *ip, loff_t loc, 
		if (!buffer_mapped(bh))

			goto unlock_out;

		/* If it's a newly allocated disk block for quota, zero it */

		if (buffer_new(bh)) {

			memset(bh->b_data, 0, bh->b_size);

			set_buffer_uptodate(bh);

		}

		if (buffer_new(bh))

			zero_user(page, pos - blocksize, bh->b_size);

	}



	if (PageUptodate(page))
@@ -723,7 +721,7 @@ static int gfs2_adjust_quota(struct gfs2_inode *ip, loff_t loc, 


	/* If quota straddles page boundary, we need to update the rest of the

	 * quota at the beginning of the next page */

	if (offset != 0) { /* first page, offset is closer to PAGE_CACHE_SIZE */

	if ((offset + sizeof(struct gfs2_quota)) > PAGE_CACHE_SIZE) {

		ptr = ptr + nbytes;

		nbytes = sizeof(struct gfs2_quota) - nbytes;

		offset = 0;