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Commit 7909b1c6 authored by Miklos Szeredi's avatar Miklos Szeredi
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fuse: don't use atomic kmap 



Don't use atomic kmap for mapping userspace buffers in device
read/write/splice.

This is necessary because the next patch (adding store notify)
requires that caller of fuse_copy_page() may sleep between
invocations.  The simplest way to ensure this is to change the atomic
kmaps to non-atomic ones.

Thankfully architectures where kmap() is not a no-op are going out of
fashion, so we can ignore the (probably negligible) performance impact
of this change.

Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
parent 815c4163

fs/fuse/dev.c

+5 −5
Original line number Diff line number Diff line
@@ -535,13 +535,13 @@ static void fuse_copy_finish(struct fuse_copy_state *cs) 
		if (!cs->write) {

			buf->ops->unmap(cs->pipe, buf, cs->mapaddr);

		} else {

			kunmap_atomic(cs->mapaddr, KM_USER0);

			kunmap(buf->page);

			buf->len = PAGE_SIZE - cs->len;

		}

		cs->currbuf = NULL;

		cs->mapaddr = NULL;

	} else if (cs->mapaddr) {

		kunmap_atomic(cs->mapaddr, KM_USER0);

		kunmap(cs->pg);

		if (cs->write) {

			flush_dcache_page(cs->pg);

			set_page_dirty_lock(cs->pg);
@@ -572,7 +572,7 @@ static int fuse_copy_fill(struct fuse_copy_state *cs) 


			BUG_ON(!cs->nr_segs);

			cs->currbuf = buf;

			cs->mapaddr = buf->ops->map(cs->pipe, buf, 1);

			cs->mapaddr = buf->ops->map(cs->pipe, buf, 0);

			cs->len = buf->len;

			cs->buf = cs->mapaddr + buf->offset;

			cs->pipebufs++;
@@ -592,7 +592,7 @@ static int fuse_copy_fill(struct fuse_copy_state *cs) 
			buf->len = 0;



			cs->currbuf = buf;

			cs->mapaddr = kmap_atomic(page, KM_USER0);

			cs->mapaddr = kmap(page);

			cs->buf = cs->mapaddr;

			cs->len = PAGE_SIZE;

			cs->pipebufs++;
@@ -611,7 +611,7 @@ static int fuse_copy_fill(struct fuse_copy_state *cs) 
			return err;

		BUG_ON(err != 1);

		offset = cs->addr % PAGE_SIZE;

		cs->mapaddr = kmap_atomic(cs->pg, KM_USER0);

		cs->mapaddr = kmap(cs->pg);

		cs->buf = cs->mapaddr + offset;

		cs->len = min(PAGE_SIZE - offset, cs->seglen);

		cs->seglen -= cs->len;