From 9fffa4e9b3b158f63334e603e610da7d529a0f9a Mon Sep 17 00:00:00 2001 From: David Howells Date: Fri, 27 Sep 2024 09:08:42 +0100 Subject: [PATCH] netfs: Advance iterator correctly rather than jumping it In netfs_write_folio(), use iov_iter_advance() to advance the folio as we split bits of it off to subrequests rather than manually jumping the ->iov_offset value around. This becomes more problematic when we use a bounce buffer made out of single-page folios to cover a multipage pagecache folio. Signed-off-by: David Howells Link: https://lore.kernel.org/r/2238548.1727424522@warthog.procyon.org.uk cc: Jeff Layton cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner --- fs/netfs/write_issue.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/fs/netfs/write_issue.c b/fs/netfs/write_issue.c index 04e66d587f777..f9761d11791dc 100644 --- a/fs/netfs/write_issue.c +++ b/fs/netfs/write_issue.c @@ -307,6 +307,7 @@ static int netfs_write_folio(struct netfs_io_request *wreq, struct netfs_io_stream *stream; struct netfs_group *fgroup; /* TODO: Use this with ceph */ struct netfs_folio *finfo; + size_t iter_off = 0; size_t fsize = folio_size(folio), flen = fsize, foff = 0; loff_t fpos = folio_pos(folio), i_size; bool to_eof = false, streamw = false; @@ -462,7 +463,12 @@ static int netfs_write_folio(struct netfs_io_request *wreq, if (choose_s < 0) break; stream = &wreq->io_streams[choose_s]; - wreq->io_iter.iov_offset = stream->submit_off; + + /* Advance the iterator(s). */ + if (stream->submit_off > iter_off) { + iov_iter_advance(&wreq->io_iter, stream->submit_off - iter_off); + iter_off = stream->submit_off; + } atomic64_set(&wreq->issued_to, fpos + stream->submit_off); stream->submit_extendable_to = fsize - stream->submit_off; @@ -477,8 +483,8 @@ static int netfs_write_folio(struct netfs_io_request *wreq, debug = true; } - wreq->io_iter.iov_offset = 0; - iov_iter_advance(&wreq->io_iter, fsize); + if (fsize > iter_off) + iov_iter_advance(&wreq->io_iter, fsize - iter_off); atomic64_set(&wreq->issued_to, fpos + fsize); if (!debug)