gfs2: Improve mmap write vs. punch_hole consistency (39c3a948) · Commits · 戴 / test

When punching a hole in a file, use filemap_write_and_wait_range to write back any dirty pages in the range of the hole. As a side effect, if the hole isn't page aligned, this marks unaligned pages at the beginning and the end of the hole read-only. This is required when the block size is smaller than the page size: when those pages are written to again after the hole punching, we must make sure that page_mkwrite is called for those pages so that the page will be fully allocated and any blocks turned into holes from the hole punching will be reallocated. (If a page is writably mapped, page_mkwrite won't be called.) Fixes xfstest generic/567. Signed-off-by:

Andreas Gruenbacher <agruenba@redhat.com>

fs/gfs2/bmap.c

+9 −2

Original line number	Diff line number	Diff line
		@@ -2440,8 +2440,16 @@ int __gfs2_punch_hole(struct file *file, loff_t offset, loff_t length)
		struct inode *inode = file_inode(file);
		struct gfs2_inode *ip = GFS2_I(inode);
		struct gfs2_sbd *sdp = GFS2_SB(inode);
		unsigned int blocksize = i_blocksize(inode);
		loff_t start, end;
		int error;

		start = round_down(offset, blocksize);
		end = round_up(offset + length, blocksize) - 1;
		error = filemap_write_and_wait_range(inode->i_mapping, start, end);
		if (error)
		return error;

		if (gfs2_is_jdata(ip))
		error = gfs2_trans_begin(sdp, RES_DINODE + 2 * RES_JDATA,
		GFS2_JTRUNC_REVOKES);
		@@ -2455,9 +2463,8 @@ int __gfs2_punch_hole(struct file *file, loff_t offset, loff_t length)
		if (error)
		goto out;
		} else {
		unsigned int start_off, end_len, blocksize;
		unsigned int start_off, end_len;

		blocksize = i_blocksize(inode);
		start_off = offset & (blocksize - 1);
		end_len = (offset + length) & (blocksize - 1);
		if (start_off) {

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