When writeback mode is enabled (-o writeback), O_APPEND handling is
done in kernel. Therefore virtiofsd clears O_APPEND flag when open.
Otherwise O_APPEND flag takes precedence over pwrite() and write
data may corrupt.
Currently clearing O_APPEND flag is done in lo_open(), but we also
need the same operation in lo_create(). So, factor out the flag
update operation in lo_open() to update_open_flags() and call it
in both lo_open() and lo_create().
This fixes the failure of xfstest generic/069 in writeback mode
(which tests O_APPEND write data integrity).
Signed-off-by: Misono Tomohiro <misono.tomoh...@jp.fujitsu.com>
---
contrib/virtiofsd/passthrough_ll.c | 56 +++++++++++++++---------------
1 file changed, 28 insertions(+), 28 deletions(-)
diff --git a/contrib/virtiofsd/passthrough_ll.c
b/contrib/virtiofsd/passthrough_ll.c
index e8892c3c32..79fb78ecce 100644
--- a/contrib/virtiofsd/passthrough_ll.c
+++ b/contrib/virtiofsd/passthrough_ll.c
@@ -1733,6 +1733,32 @@ static void lo_releasedir(fuse_req_t req, fuse_ino_t
ino, struct fuse_file_info
fuse_reply_err(req, 0);
}
+static void update_open_flags(int writeback, struct fuse_file_info *fi)
+{
+ /* With writeback cache, kernel may send read requests even
+ when userspace opened write-only */
+ if (writeback && (fi->flags & O_ACCMODE) == O_WRONLY) {
+ fi->flags &= ~O_ACCMODE;
+ fi->flags |= O_RDWR;
+ }
+
+ /* With writeback cache, O_APPEND is handled by the kernel.
+ This breaks atomicity (since the file may change in the
+ underlying filesystem, so that the kernel's idea of the
+ end of the file isn't accurate anymore). In this example,
+ we just accept that. A more rigorous filesystem may want
+ to return an error here */
+ if (writeback && (fi->flags & O_APPEND))
+ fi->flags &= ~O_APPEND;
+
+ /*
+ * O_DIRECT in guest should not necessarily mean bypassing page
+ * cache on host as well. If somebody needs that behavior, it
+ * probably should be a configuration knob in daemon.
+ */
+ fi->flags &= ~O_DIRECT;
+}
+
static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name,
mode_t mode, struct fuse_file_info *fi)
{
@@ -1760,12 +1786,7 @@ static void lo_create(fuse_req_t req, fuse_ino_t parent,
const char *name,
if (err)
goto out;
- /*
- * O_DIRECT in guest should not necessarily mean bypassing page
- * cache on host as well. If somebody needs that behavior, it
- * probably should be a configuration knob in daemon.
- */
- fi->flags &= ~O_DIRECT;
+ update_open_flags(lo->writeback, fi);
fd = openat(parent_inode->fd, name,
(fi->flags | O_CREAT) & ~O_NOFOLLOW, mode);
@@ -1966,28 +1987,7 @@ static void lo_open(fuse_req_t req, fuse_ino_t ino,
struct fuse_file_info *fi)
fuse_log(FUSE_LOG_DEBUG, "lo_open(ino=%" PRIu64 ", flags=%d)\n", ino,
fi->flags);
- /* With writeback cache, kernel may send read requests even
- when userspace opened write-only */
- if (lo->writeback && (fi->flags & O_ACCMODE) == O_WRONLY) {
- fi->flags &= ~O_ACCMODE;
- fi->flags |= O_RDWR;
- }
-
- /* With writeback cache, O_APPEND is handled by the kernel.
- This breaks atomicity (since the file may change in the
- underlying filesystem, so that the kernel's idea of the
- end of the file isn't accurate anymore). In this example,
- we just accept that. A more rigorous filesystem may want
- to return an error here */
- if (lo->writeback && (fi->flags & O_APPEND))
- fi->flags &= ~O_APPEND;
-
- /*
- * O_DIRECT in guest should not necessarily mean bypassing page
- * cache on host as well. If somebody needs that behavior, it
- * probably should be a configuration knob in daemon.
- */
- fi->flags &= ~O_DIRECT;
+ update_open_flags(lo->writeback, fi);
sprintf(buf, "%i", lo_fd(req, ino));
fd = openat(lo->proc_self_fd, buf, fi->flags & ~O_NOFOLLOW);
--
2.21.0
