From 8db55c5cd831a786a1a2a2d391aa80354535a353 Mon Sep 17 00:00:00 2001 From: Paulo Alcantara Date: Sat, 26 Sep 2026 17:44:50 -0300 Subject: [PATCH] netfs: zero gaps in read-gaps folio to avoid writing back stale data netfs_read_gaps() leaves gaps around a streaming write's dirty region unread on the server side, so a short/EOF response there left stale folio content that later got written back. Zero it after the read completes, not before: netfs_wait_for_read() returns rreq->transferred once ret >= 0, so build an iterator over the same bvec array the read used, advance past ret, and zero the rest. The dirty region already maps to sink pages in that array rather than the real folio, so this can't touch it, and only the actual shortfall gets zeroed instead of the whole gap upfront. Fixes: ee4cdf7ba857 ("netfs: Speed up buffered reading") Reviewed-by: David Howells Reviewed-by: Namjae Jeon Signed-off-by: Paulo Alcantara Cc: Christian Brauner Cc: Matthew Wilcox Cc: Ronnie Sahlberg Cc: Shyam Prasad N Cc: Tom Talpey Cc: Bharath SM Cc: stable@vger.kernel.org --- fs/netfs/buffered_read.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/fs/netfs/buffered_read.c b/fs/netfs/buffered_read.c index 105194de6e13..e6506942aeda 100644 --- a/fs/netfs/buffered_read.c +++ b/fs/netfs/buffered_read.c @@ -541,6 +541,13 @@ static int netfs_read_gaps(struct file *file, struct folio *folio) ret = netfs_wait_for_read(rreq); if (ret >= 0) { + if (ret < flen) { + struct iov_iter iter; + + iov_iter_bvec(&iter, ITER_DEST, bvec, i, flen); + iov_iter_advance(&iter, ret); + iov_iter_zero(flen - ret, &iter); + } if (group) folio_change_private(folio, group); else