Commit e7fdf004 authored Dec 12, 2017 by Andreas Gruenbacher Committed by Bob Peterson Jan 17, 2018

gfs2: Remove minor gfs2_journaled_truncate inefficiencies

First, this function truncates the file in chunks. When the original
file size isn't block aligned, each chunk that is truncated will remain
be misaligned. This is inefficient.

Second, this function doesn't recognize where holes are, so it loops
through them. For each chunk of a hole, it creates a new transaction.
At least avoid creating another transactions whe the current one is
still empty. (An better fix would be to skip large holes, of course.)

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>

parent 8b5860a3

fs/gfs2/bmap.c

+13 −0

Original line number	Diff line number	Diff line
		@@ -1003,11 +1003,24 @@ static int gfs2_journaled_truncate(struct inode *inode, u64 oldsize, u64 newsize
		int error;

		while (oldsize != newsize) {
		struct gfs2_trans *tr;
		unsigned int offs;

		chunk = oldsize - newsize;
		if (chunk > max_chunk)
		chunk = max_chunk;

		offs = oldsize & ~PAGE_MASK;
		if (offs && chunk > PAGE_SIZE)
		chunk = offs + ((chunk - offs) & PAGE_MASK);

		truncate_pagecache(inode, oldsize - chunk);
		oldsize -= chunk;

		tr = current->journal_info;
		if (!test_bit(TR_TOUCHED, &tr->tr_flags))
		continue;

		gfs2_trans_end(sdp);
		error = gfs2_trans_begin(sdp, RES_DINODE, GFS2_JTRUNC_REVOKES);
		if (error)

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