In preparation for protecting the dax read(2) path from media errors with copy_to_iter_mcsafe() (via dax_copy_to_iter()), convert the implementation to report the bytes successfully transferred.
Cc: <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Tony Luck <[email protected]> Cc: Al Viro <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Linus Torvalds <[email protected]> Signed-off-by: Dan Williams <[email protected]> --- fs/dax.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) diff --git a/fs/dax.c b/fs/dax.c index a64afdf7ec0d..34a2d435ae4b 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -991,6 +991,7 @@ dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data, struct iov_iter *iter = data; loff_t end = pos + length, done = 0; ssize_t ret = 0; + size_t xfer; int id; if (iov_iter_rw(iter) == READ) { @@ -1054,19 +1055,20 @@ dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data, * vfs_write(), depending on which operation we are doing. */ if (iov_iter_rw(iter) == WRITE) - map_len = dax_copy_from_iter(dax_dev, pgoff, kaddr, + xfer = dax_copy_from_iter(dax_dev, pgoff, kaddr, map_len, iter); else - map_len = dax_copy_to_iter(dax_dev, pgoff, kaddr, + xfer = dax_copy_to_iter(dax_dev, pgoff, kaddr, map_len, iter); - if (map_len <= 0) { - ret = map_len ? map_len : -EFAULT; - break; - } - pos += map_len; - length -= map_len; - done += map_len; + pos += xfer; + length -= xfer; + done += xfer; + + if (xfer == 0) + ret = -EFAULT; + if (xfer < map_len) + break; } dax_read_unlock(id);
