From e00e99ba6c6b8e5239e75cd6684a6827d93c39a2 Mon Sep 17 00:00:00 2001 From: David Howells Date: Sat, 24 Aug 2024 12:56:53 +0100 Subject: netfs: Fix interaction of streaming writes with zero-point tracker When a folio that is marked for streaming write (dirty, but not uptodate, with partial content specified in the private data) is written back, the folio is effectively switched to the blank state upon completion of the write. This means that if we want to read it in future, we need to reread the whole folio. However, if the folio is above the zero_point position, when it is read back, it will just be cleared and the read skipped, leading to apparent local corruption. Fix this by increasing the zero_point to the end of the dirty data in the folio when clearing the folio state after writeback. This is analogous to the folio having ->release_folio() called upon it. This was causing the config.log generated by configuring a cpython tree on a cifs share to get corrupted because the scripts involved were appending text to the file in small pieces. Fixes: 288ace2f57c9 ("netfs: New writeback implementation") Signed-off-by: David Howells Link: https://lore.kernel.org/r/563286.1724500613@warthog.procyon.org.uk cc: Steve French cc: Paulo Alcantara cc: Jeff Layton cc: linux-cifs@vger.kernel.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner --- fs/netfs/write_collect.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'fs/netfs') diff --git a/fs/netfs/write_collect.c b/fs/netfs/write_collect.c index 426cf87aaf2e..ae7a2043f670 100644 --- a/fs/netfs/write_collect.c +++ b/fs/netfs/write_collect.c @@ -33,6 +33,7 @@ int netfs_folio_written_back(struct folio *folio) { enum netfs_folio_trace why = netfs_folio_trace_clear; + struct netfs_inode *ictx = netfs_inode(folio->mapping->host); struct netfs_folio *finfo; struct netfs_group *group = NULL; int gcount = 0; @@ -41,6 +42,12 @@ int netfs_folio_written_back(struct folio *folio) /* Streaming writes cannot be redirtied whilst under writeback, * so discard the streaming record. */ + unsigned long long fend; + + fend = folio_pos(folio) + finfo->dirty_offset + finfo->dirty_len; + if (fend > ictx->zero_point) + ictx->zero_point = fend; + folio_detach_private(folio); group = finfo->netfs_group; gcount++; -- cgit v1.2.3