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authorCsaba Henk <csaba@gluster.com>2009-09-23 10:34:38 +0000
committerAnand V. Avati <avati@dev.gluster.com>2009-09-23 09:19:29 -0700
commita484a0c47ef6468c1615aa78795880e71347f709 (patch)
treea16ec602af03258c9b36cfa7cbcab40b939a7162 /xlators/mount/fuse
parent270a473ddaa076af5b3c8c455c7642932dabb479 (diff)
fuse: emit a flush from release if we didn't get an adjacent FLUSH message from the kernel
Signed-off-by: Anand V. Avati <avati@dev.gluster.com> BUG: 223 (flush not sent) URL: http://bugs.gluster.com/cgi-bin/bugzilla3/show_bug.cgi?id=223
Diffstat (limited to 'xlators/mount/fuse')
-rw-r--r--xlators/mount/fuse/src/fuse-bridge.c55
1 files changed, 50 insertions, 5 deletions
diff --git a/xlators/mount/fuse/src/fuse-bridge.c b/xlators/mount/fuse/src/fuse-bridge.c
index 9d358984b..e2f0a916d 100644
--- a/xlators/mount/fuse/src/fuse-bridge.c
+++ b/xlators/mount/fuse/src/fuse-bridge.c
@@ -1587,6 +1587,8 @@ fuse_flush (fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi)
state = state_from_req (req);
fd = FI_TO_FD (fi);
state->fd = fd;
+ if (fd)
+ fd->flush_unique = req_callid (req);
gf_log ("glusterfs-fuse", GF_LOG_TRACE,
"%"PRId64": FLUSH %p", req_callid (req), fd);
@@ -1602,18 +1604,61 @@ static void
fuse_release (fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi)
{
fuse_state_t *state = NULL;
+ fd_t *fd = NULL;
+ int do_flush = 0;
state = state_from_req (req);
- state->fd = FI_TO_FD (fi);
+ fd = FI_TO_FD (fi);
+ state->fd = fd;
+#ifdef GF_LINUX_HOST_OS
+ /* This is an ugly Linux specific hack, relying on subtle
+ * implementation details.
+ *
+ * The self-heal algorithm of replicate relies on being
+ * notified by means of a flush fop whenever a consumer
+ * of a file is done with that file. If this happens
+ * from userspace by means of close(2) or process termination,
+ * the kernel sends us a FLUSH message which we can handle with
+ * the flush fop (nb. this mechanism itself is Linux specific!!).
+ *
+ * However, if it happens from a kernel context, we get no FLUSH,
+ * just the final RELEASE when all references to the file are gone.
+ * We try to guess that this is the case by checking if the last FLUSH
+ * on the file was just the previous message. If not, we conjecture
+ * that this release is from a kernel context and call the flush fop
+ * here.
+ *
+ * Note #1: we check the above condition by means of looking at
+ * the "unique" values of the FUSE messages, relying on which is
+ * a big fat NO NO NO in any sane code.
+ *
+ * Note #2: there is no guarantee against false positives (in theory
+ * it's possible that the scheduler arranges an unrelated FUSE message
+ * in between FLUSH and RELEASE, although it seems to be unlikely), but
+ * extra flushes are not a problem.
+ *
+ * Note #3: cf. Bug #223.
+ */
+
+ if (fd && fd->flush_unique + 1 != req_callid (req))
+ do_flush = 1;
+#endif
gf_log ("glusterfs-fuse", GF_LOG_TRACE,
- "%"PRId64": RELEASE %p", req_callid (req), state->fd);
+ "%"PRId64": RELEASE %p%s", req_callid (req), fd,
+ do_flush ? " (FLUSH implied)" : "");
- fd_unref (state->fd);
+ if (do_flush) {
+ FUSE_FOP (state, fuse_err_cbk, GF_FOP_FLUSH, flush, fd);
+ fd_unref (fd);
+ } else {
+ fd_unref (fd);
- fuse_reply_err (req, 0);
+ fuse_reply_err (req, 0);
+
+ free_state (state);
+ }
- free_state (state);
return;
}