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fuse: Use copy_page() when possible for argument copies #119

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fuse: Use copy_page() when possible for argument copies #119

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30 changes: 22 additions & 8 deletions fs/fuse/dev.c
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Original file line number Diff line number Diff line change
Expand Up @@ -805,17 +805,28 @@ static int fuse_copy_fill(struct fuse_copy_state *cs)
}

/* Do as much copy to/from userspace buffer as we can */
static int fuse_copy_do(struct fuse_copy_state *cs, void **val, unsigned *size)
static int fuse_copy_do(struct fuse_copy_state *cs, void **val, unsigned *size,
bool use_copy_page)
{
unsigned ncpy = min(*size, cs->len);
if (val) {
void *pgaddr = kmap_local_page(cs->pg);
void *buf = pgaddr + cs->offset;
void *src, *dst;

if (cs->write)
memcpy(buf, *val, ncpy);
else
memcpy(*val, buf, ncpy);
if (cs->write) {
src = *val;
dst = buf;
} else {
src = buf;
dst = *val;
}

if (use_copy_page) {
copy_page(dst, src);
} else {
memcpy(dst, src, ncpy);
}

kunmap_local(pgaddr);
*val += ncpy;
Expand Down Expand Up @@ -1022,10 +1033,13 @@ static int fuse_copy_page(struct fuse_copy_state *cs, struct page **pagep,
if (page) {
void *mapaddr = kmap_local_page(page);
void *buf = mapaddr + offset;
offset += fuse_copy_do(cs, &buf, &count);
bool use_copy_page = (count == PAGE_SIZE);

offset += fuse_copy_do(cs, &buf, &count, use_copy_page);

kunmap_local(mapaddr);
} else
offset += fuse_copy_do(cs, NULL, &count);
offset += fuse_copy_do(cs, NULL, &count, false);
}
if (page && !cs->write)
flush_dcache_page(page);
Expand Down Expand Up @@ -1064,7 +1078,7 @@ static int fuse_copy_one(struct fuse_copy_state *cs, void *val, unsigned size)
if (err)
return err;
}
fuse_copy_do(cs, &val, &size);
fuse_copy_do(cs, &val, &size, false);
}
return 0;
}
Expand Down