137 lines
5.1 KiB
Diff
137 lines
5.1 KiB
Diff
From 9b5fbc95a287b2ce9448142194b161d8360d5e4e Mon Sep 17 00:00:00 2001
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From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
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Date: Mon, 27 Jan 2020 19:02:15 +0100
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Subject: [PATCH 104/116] virtiofsd: Fix data corruption with O_APPEND write in
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writeback mode
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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RH-Author: Dr. David Alan Gilbert <dgilbert@redhat.com>
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Message-id: <20200127190227.40942-101-dgilbert@redhat.com>
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Patchwork-id: 93556
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O-Subject: [RHEL-AV-8.2 qemu-kvm PATCH 100/112] virtiofsd: Fix data corruption with O_APPEND write in writeback mode
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Bugzilla: 1694164
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RH-Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Sergio Lopez Pascual <slp@redhat.com>
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From: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>
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When writeback mode is enabled (-o writeback), O_APPEND handling is
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done in kernel. Therefore virtiofsd clears O_APPEND flag when open.
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Otherwise O_APPEND flag takes precedence over pwrite() and write
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data may corrupt.
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Currently clearing O_APPEND flag is done in lo_open(), but we also
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need the same operation in lo_create(). So, factor out the flag
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update operation in lo_open() to update_open_flags() and call it
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in both lo_open() and lo_create().
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This fixes the failure of xfstest generic/069 in writeback mode
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(which tests O_APPEND write data integrity).
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Signed-off-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>
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Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
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Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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(cherry picked from commit 8e4e41e39eac5ee5f378d66f069a2f70a1734317)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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tools/virtiofsd/passthrough_ll.c | 66 ++++++++++++++++++++--------------------
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1 file changed, 33 insertions(+), 33 deletions(-)
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diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
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index 948cb19..4c61ac5 100644
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--- a/tools/virtiofsd/passthrough_ll.c
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+++ b/tools/virtiofsd/passthrough_ll.c
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@@ -1692,6 +1692,37 @@ static void lo_releasedir(fuse_req_t req, fuse_ino_t ino,
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fuse_reply_err(req, 0);
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}
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+static void update_open_flags(int writeback, struct fuse_file_info *fi)
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+{
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+ /*
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+ * With writeback cache, kernel may send read requests even
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+ * when userspace opened write-only
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+ */
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+ if (writeback && (fi->flags & O_ACCMODE) == O_WRONLY) {
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+ fi->flags &= ~O_ACCMODE;
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+ fi->flags |= O_RDWR;
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+ }
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+
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+ /*
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+ * With writeback cache, O_APPEND is handled by the kernel.
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+ * This breaks atomicity (since the file may change in the
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+ * underlying filesystem, so that the kernel's idea of the
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+ * end of the file isn't accurate anymore). In this example,
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+ * we just accept that. A more rigorous filesystem may want
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+ * to return an error here
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+ */
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+ if (writeback && (fi->flags & O_APPEND)) {
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+ fi->flags &= ~O_APPEND;
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+ }
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+
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+ /*
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+ * O_DIRECT in guest should not necessarily mean bypassing page
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+ * cache on host as well. If somebody needs that behavior, it
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+ * probably should be a configuration knob in daemon.
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+ */
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+ fi->flags &= ~O_DIRECT;
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+}
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+
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static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name,
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mode_t mode, struct fuse_file_info *fi)
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{
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@@ -1721,12 +1752,7 @@ static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name,
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goto out;
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}
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- /*
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- * O_DIRECT in guest should not necessarily mean bypassing page
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- * cache on host as well. If somebody needs that behavior, it
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- * probably should be a configuration knob in daemon.
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- */
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- fi->flags &= ~O_DIRECT;
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+ update_open_flags(lo->writeback, fi);
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fd = openat(parent_inode->fd, name, (fi->flags | O_CREAT) & ~O_NOFOLLOW,
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mode);
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@@ -1936,33 +1962,7 @@ static void lo_open(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi)
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fuse_log(FUSE_LOG_DEBUG, "lo_open(ino=%" PRIu64 ", flags=%d)\n", ino,
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fi->flags);
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- /*
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- * With writeback cache, kernel may send read requests even
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- * when userspace opened write-only
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- */
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- if (lo->writeback && (fi->flags & O_ACCMODE) == O_WRONLY) {
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- fi->flags &= ~O_ACCMODE;
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- fi->flags |= O_RDWR;
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- }
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-
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- /*
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- * With writeback cache, O_APPEND is handled by the kernel.
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- * This breaks atomicity (since the file may change in the
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- * underlying filesystem, so that the kernel's idea of the
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- * end of the file isn't accurate anymore). In this example,
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- * we just accept that. A more rigorous filesystem may want
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- * to return an error here
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- */
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- if (lo->writeback && (fi->flags & O_APPEND)) {
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- fi->flags &= ~O_APPEND;
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- }
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-
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- /*
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- * O_DIRECT in guest should not necessarily mean bypassing page
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- * cache on host as well. If somebody needs that behavior, it
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- * probably should be a configuration knob in daemon.
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- */
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- fi->flags &= ~O_DIRECT;
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+ update_open_flags(lo->writeback, fi);
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sprintf(buf, "%i", lo_fd(req, ino));
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fd = openat(lo->proc_self_fd, buf, fi->flags & ~O_NOFOLLOW);
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--
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1.8.3.1
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