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From 90092b0c276f599bbe415ecc3051ca12d99461b6 Mon Sep 17 00:00:00 2001
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From: Raghavendra G <rgowdapp@redhat.com>
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Date: Sat, 17 Mar 2018 13:16:59 +0530
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Subject: [PATCH 263/271] server/resolver: don't trust inode-table for
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RESOLVE_NOT
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There have been known races between fops which add a dentry (like
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lookup, create, mknod etc) and fops that remove a dentry (like rename,
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unlink, rmdir etc) due to which stale dentries are left out in inode
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table even though the dentry doesn't exist on backend. For eg.,
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consider a lookup (parent/bname) and unlink (parent/bname) racing in
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the following order:
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* lookup hits storage/posix and finds that dentry exists
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* unlink removes the dentry on storage/posix
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* unlink reaches protocol/server where the dentry (parent/bname) is
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unlinked from the inode
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* lookup reaches protocol/server and creates a dentry (parent/bname)
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on the inode
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Now we've a stale dentry (parent/bname) associated with the inode in
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itable. This situation is bad for fops like link, create etc which
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invoke resolver with type RESOLVE_NOT. These fops fail with EEXIST
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even though there is no such dentry on backend fs. This issue can be
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solved in two ways:
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* Enable "dentry fop serializer" xlator [1].
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# gluster volume set features.sdfs on
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* Make sure resolver does a lookup on backend when it finds a dentry
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in itable and validates the state of itable.
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- If a dentry is not found, unlink those stale dentries from itable
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and continue with fop
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- If dentry is found, fail the fop with EEXIST
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This patch implements second solution as sdfs is not enabled by
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default in brick xlator stack. Once sdfs is enabled by default, this
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patch can be reverted.
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[1] https://github.com/gluster/glusterfs/issues/397
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>Change-Id: Ia8bb0cf97f97cb0e72639bce8aadb0f6d3f4a34a
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>updates: bz#1543279
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>BUG: 1543279
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>Signed-off-by: Raghavendra G <rgowdapp@redhat.com>
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upstream patch: https://review.gluster.org/19732
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BUG: 1488120
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Change-Id: I78df4f6751e5db1fc659ee15d92b76d1486455f0
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Signed-off-by: Raghavendra G <rgowdapp@redhat.com>
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Reviewed-on: https://code.engineering.redhat.com/gerrit/138152
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Tested-by: RHGS Build Bot <nigelb@redhat.com>
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Reviewed-by: Nithya Balachandran <nbalacha@redhat.com>
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---
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xlators/protocol/server/src/server-resolve.c | 27 +++++++++++++++++++++++----
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1 file changed, 23 insertions(+), 4 deletions(-)
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diff --git a/xlators/protocol/server/src/server-resolve.c b/xlators/protocol/server/src/server-resolve.c
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index d0126aa..6ffb909 100644
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--- a/xlators/protocol/server/src/server-resolve.c
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+++ b/xlators/protocol/server/src/server-resolve.c
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@@ -58,10 +58,27 @@ resolve_gfid_entry_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
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if (op_ret == -1) {
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if (op_errno == ENOENT) {
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- gf_msg_debug (this->name, 0, "%s/%s: failed to resolve"
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- " (%s)",
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+ gf_msg_debug (this->name, 0,
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+ "%s/%s: failed to resolve (%s)",
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uuid_utoa (resolve_loc->pargfid),
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resolve_loc->name, strerror (op_errno));
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+ if (resolve->type == RESOLVE_NOT) {
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+ do {
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+ inode = inode_grep (state->itable,
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+ resolve_loc->parent,
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+ resolve->bname);
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+
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+ if (inode) {
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+ gf_msg_debug (this->name, 0, "%s/%s: "
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+ "removing stale dentry",
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+ uuid_utoa (resolve_loc->pargfid),
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+ resolve->bname);
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+ inode_unlink (inode,
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+ resolve_loc->parent,
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+ resolve->bname);
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+ }
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+ } while (inode);
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+ }
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} else {
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gf_msg (this->name, GF_LOG_WARNING, op_errno,
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PS_MSG_GFID_RESOLVE_FAILED, "%s/%s: failed to "
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@@ -318,11 +335,13 @@ resolve_entry_simple (call_frame_t *frame)
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if (resolve->type == RESOLVE_NOT) {
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gf_msg_debug (this->name, 0, "inode (pointer: %p gfid:%s found"
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- " for path (%s) while type is RESOLVE_NOT",
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+ " for path (%s) while type is RESOLVE_NOT. "
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+ "Performing lookup on backend to rule out any "
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+ "possible stale dentries in inode table",
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inode, uuid_utoa (inode->gfid), resolve->path);
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resolve->op_ret = -1;
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resolve->op_errno = EEXIST;
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- ret = -1;
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+ ret = 1;
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goto out;
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}
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--
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1.8.3.1
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