[PATCH v2 7/7] fuse: convert direct IO paths to use FOLL_PIN

John Hubbard
2022-08-31T04:20:23Z

Convert the fuse filesystem to use pin_user_pages_fast() and
unpin_user_page(), instead of get_user_pages_fast() and put_page().

The user of pin_user_pages_fast() depends upon:

1) CONFIG_BLK_USE_PIN_USER_PAGES_FOR_DIO, and

2) User-space-backed pages or ITER_BVEC pages.

Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
fs/fuse/dev.c | 11 +++++++++--
fs/fuse/file.c | 32 +++++++++++++++++++++-----------
fs/fuse/fuse_i.h | 1 +
3 files changed, 31 insertions(+), 13 deletions(-)

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 51897427a534..5de98a7a45b1 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -675,7 +675,12 @@ static void fuse_copy_finish(struct fuse_copy_state *cs)
flush_dcache_page(cs->pg);
set_page_dirty_lock(cs->pg);
}
- put_page(cs->pg);
+ if (!cs->pipebufs &&
+ (user_backed_iter(cs->iter) || iov_iter_is_bvec(cs->iter)))
+ dio_w_unpin_user_page(cs->pg);
+
+ else
+ put_page(cs->pg);
}
cs->pg = NULL;
}
@@ -730,7 +735,9 @@ static int fuse_copy_fill(struct fuse_copy_state *cs)
}
} else {
size_t off;
- err = iov_iter_get_pages2(cs->iter, &page, PAGE_SIZE, 1, &off);
+
+ err = dio_w_iov_iter_pin_pages(cs->iter, &page, PAGE_SIZE, 1,
+ &off);
if (err < 0)
return err;
BUG_ON(!err);
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 1a3afd469e3a..01da38928d0b 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -625,14 +625,19 @@ void fuse_read_args_fill(struct fuse_io_args *ia, struct file *file, loff_t pos,
}

static void fuse_release_user_pages(struct fuse_args_pages *ap,
- bool should_dirty)
+ bool should_dirty, bool is_user_or_bvec)
{
unsigned int i;

- for (i = 0; i < ap->num_pages; i++) {
- if (should_dirty)
- set_page_dirty_lock(ap->pages[i]);
- put_page(ap->pages[i]);
+ if (is_user_or_bvec) {
+ dio_w_unpin_user_pages_dirty_lock(ap->pages, ap->num_pages,
+ should_dirty);
+ } else {
+ for (i = 0; i < ap->num_pages; i++) {
+ if (should_dirty)
+ set_page_dirty_lock(ap->pages[i]);
+ put_page(ap->pages[i]);
+ }
}
}

@@ -733,7 +738,7 @@ static void fuse_aio_complete_req(struct fuse_mount *fm, struct fuse_args *args,
struct fuse_io_priv *io = ia->io;
ssize_t pos = -1;

- fuse_release_user_pages(&ia->ap, io->should_dirty);
+ fuse_release_user_pages(&ia->ap, io->should_dirty, io->is_user_or_bvec);

if (err) {
/* Nothing */
@@ -1414,10 +1419,10 @@ static int fuse_get_user_pages(struct fuse_args_pages *ap, struct iov_iter *ii,
while (nbytes < *nbytesp && ap->num_pages < max_pages) {
unsigned npages;
size_t start;
- ret = iov_iter_get_pages2(ii, &ap->pages[ap->num_pages],
- *nbytesp - nbytes,
- max_pages - ap->num_pages,
- &start);
+ ret = dio_w_iov_iter_pin_pages(ii, &ap->pages[ap->num_pages],
+ *nbytesp - nbytes,
+ max_pages - ap->num_pages,
+ &start);
if (ret < 0)
break;

@@ -1483,6 +1488,10 @@ ssize_t fuse_direct_io(struct fuse_io_priv *io, struct iov_iter *iter,
fl_owner_t owner = current->files;
size_t nbytes = min(count, nmax);

+ /* For use in fuse_release_user_pages(): */
+ io->is_user_or_bvec = user_backed_iter(iter) ||
+ iov_iter_is_bvec(iter);
+
err = fuse_get_user_pages(&ia->ap, iter, &nbytes, write,
max_pages);
if (err && !nbytes)
@@ -1498,7 +1507,8 @@ ssize_t fuse_direct_io(struct fuse_io_priv *io, struct iov_iter *iter,
}

if (!io->async || nres < 0) {
- fuse_release_user_pages(&ia->ap, io->should_dirty);
+ fuse_release_user_pages(&ia->ap, io->should_dirty,
+ io->is_user_or_bvec);
fuse_io_free(ia);
}
ia = NULL;
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 488b460e046f..6ee7f72e29eb 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -290,6 +290,7 @@ struct fuse_io_priv {
struct kiocb *iocb;
struct completion *done;
bool blocking;
+ bool is_user_or_bvec;
};

#define FUSE_IO_PRIV_SYNC(i) \
--
2.37.2