From: David Howells <dhowells@redhat.com>
To: Christian Brauner <christian@brauner.io>
Cc: dhowells@redhat.com, Jeff Layton <jlayton@kernel.org>,
Gao Xiang <hsiangkao@linux.alibaba.com>,
Dominique Martinet <asmadeus@codewreck.org>,
Matthew Wilcox <willy@infradead.org>,
Steve French <smfrench@gmail.com>,
Marc Dionne <marc.dionne@auristor.com>,
Paulo Alcantara <pc@manguebit.com>,
Shyam Prasad N <sprasad@microsoft.com>,
Tom Talpey <tom@talpey.com>,
Eric Van Hensbergen <ericvh@kernel.org>,
Ilya Dryomov <idryomov@gmail.com>,
netfs@lists.linux.dev, linux-cachefs@redhat.com,
linux-afs@lists.infradead.org, linux-cifs@vger.kernel.org,
linux-nfs@vger.kernel.org, ceph-devel@vger.kernel.org,
v9fs@lists.linux.dev, linux-erofs@lists.ozlabs.org,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
Latchesar Ionkov <lucho@ionkov.net>,
Christian Schoenebeck <linux_oss@crudebyte.com>
Subject: Re: [PATCH v2 14/22] netfs: New writeback implementation
Date: Wed, 01 May 2024 18:00:59 +0100 [thread overview]
Message-ID: <458060.1714582859@warthog.procyon.org.uk> (raw)
In-Reply-To: <20240430140056.261997-15-dhowells@redhat.com>
This needs the attached change. It needs to allow for netfs_perform_write()
changing i_size whilst we're doing writeback. The issue is that i_size is
cached in the netfs_io_request struct (as that's what we're going to tell the
server the new i_size should be), but we're not updating this properly if
i_size moves between us creating the request and us deciding to write out the
folio in which i_size was when we created the request.
This can lead to the folio_zero_segment() that can be seen in the patch below
clearing the wrong amount of the final page - assuming it's still the final
page.
David
---
diff --git a/fs/netfs/write_issue.c b/fs/netfs/write_issue.c
index 69c50f4cbf41..e190043bc0da 100644
--- a/fs/netfs/write_issue.c
+++ b/fs/netfs/write_issue.c
@@ -315,13 +315,19 @@ static int netfs_write_folio(struct netfs_io_request *wreq,
struct netfs_group *fgroup; /* TODO: Use this with ceph */
struct netfs_folio *finfo;
size_t fsize = folio_size(folio), flen = fsize, foff = 0;
- loff_t fpos = folio_pos(folio);
+ loff_t fpos = folio_pos(folio), i_size;
bool to_eof = false, streamw = false;
bool debug = false;
_enter("");
- if (fpos >= wreq->i_size) {
+ /* netfs_perform_write() may shift i_size around the page or from out
+ * of the page to beyond it, but cannot move i_size into or through the
+ * page since we have it locked.
+ */
+ i_size = i_size_read(wreq->inode);
+
+ if (fpos >= i_size) {
/* mmap beyond eof. */
_debug("beyond eof");
folio_start_writeback(folio);
@@ -332,6 +338,9 @@ static int netfs_write_folio(struct netfs_io_request *wreq,
return 0;
}
+ if (fpos + fsize > wreq->i_size)
+ wreq->i_size = i_size;
+
fgroup = netfs_folio_group(folio);
finfo = netfs_folio_info(folio);
if (finfo) {
@@ -342,14 +351,14 @@ static int netfs_write_folio(struct netfs_io_request *wreq,
if (wreq->origin == NETFS_WRITETHROUGH) {
to_eof = false;
- if (flen > wreq->i_size - fpos)
- flen = wreq->i_size - fpos;
- } else if (flen > wreq->i_size - fpos) {
- flen = wreq->i_size - fpos;
+ if (flen > i_size - fpos)
+ flen = i_size - fpos;
+ } else if (flen > i_size - fpos) {
+ flen = i_size - fpos;
if (!streamw)
folio_zero_segment(folio, flen, fsize);
to_eof = true;
- } else if (flen == wreq->i_size - fpos) {
+ } else if (flen == i_size - fpos) {
to_eof = true;
}
flen -= foff;
prev parent reply other threads:[~2024-05-01 17:01 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-30 14:00 [PATCH v2 00/22] netfs, afs, 9p, cifs: Rework netfs to use ->writepages() to copy to cache David Howells
2024-04-30 14:00 ` [PATCH v2 01/22] netfs: Update i_blocks when write committed to pagecache David Howells
2024-04-30 14:00 ` [PATCH v2 02/22] netfs: Replace PG_fscache by setting folio->private and marking dirty David Howells
2024-04-30 14:00 ` [PATCH v2 03/22] mm: Remove the PG_fscache alias for PG_private_2 David Howells
2024-04-30 14:00 ` [PATCH v2 04/22] netfs: Remove deprecated use of PG_private_2 as a second writeback flag David Howells
2024-04-30 14:00 ` [PATCH v2 05/22] netfs: Make netfs_io_request::subreq_counter an atomic_t David Howells
2024-04-30 14:00 ` [PATCH v2 06/22] netfs: Use subreq_counter to allocate subreq debug_index values David Howells
2024-04-30 14:00 ` [PATCH v2 07/22] mm: Provide a means of invalidation without using launder_folio David Howells
2024-05-01 4:41 ` Christoph Hellwig
2024-04-30 14:00 ` [PATCH v2 08/22] 9p: Use alternative invalidation to " David Howells
2024-04-30 14:00 ` [PATCH v2 09/22] afs: " David Howells
2024-04-30 14:00 ` [PATCH v2 10/22] netfs: Remove ->launder_folio() support David Howells
2024-04-30 14:00 ` [PATCH v2 11/22] netfs: Use mempools for allocating requests and subrequests David Howells
2024-04-30 14:00 ` [PATCH v2 12/22] mm: Export writeback_iter() David Howells
2024-04-30 14:00 ` [PATCH v2 13/22] netfs: Switch to using unsigned long long rather than loff_t David Howells
2024-04-30 14:00 ` [PATCH v2 14/22] netfs: New writeback implementation David Howells
2024-04-30 14:00 ` [PATCH v2 15/22] netfs: Add some write-side stats and clean up some stat names David Howells
2024-04-30 14:00 ` [PATCH v2 16/22] netfs, afs: Implement helpers for new write code David Howells
2024-04-30 14:00 ` [PATCH v2 17/22] netfs, 9p: " David Howells
2024-04-30 14:00 ` [PATCH v2 18/22] netfs, cachefiles: " David Howells
2024-04-30 14:00 ` [PATCH v2 19/22] netfs: Cut over to using new writeback code David Howells
2024-04-30 14:00 ` [PATCH v2 20/22] netfs: Remove the old " David Howells
2024-04-30 14:00 ` [PATCH v2 21/22] netfs: Miscellaneous tidy ups David Howells
2024-04-30 14:00 ` [PATCH v2 22/22] netfs, afs: Use writeback retry to deal with alternate keys David Howells
2024-05-01 11:51 ` [PATCH v2 07/22] mm: Provide a means of invalidation without using launder_folio David Howells
2024-05-01 17:00 ` David Howells [this message]
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