features/locks: fcntl(3) on F_GETLK must return first conflicting lock

- Added test program, getlk_owner.c to capture the bug when regressed.

Change-Id: Ic2a0f6fa8d094c0f2e9f4a6febd278d4a2948223
BUG: 869724
Signed-off-by: Krishnan Parthasarathi <kparthas@redhat.com>
Reviewed-on: http://review.gluster.org/4164
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

tests/bugs/bug-869724.t

@@ -0,0 +1,61 @@
+#!/bin/bash
+
+. $(dirname $0)/../include.rc
+
+cleanup;
+
+
+## Start and create a volume
+TEST glusterd
+TEST pidof glusterd
+
+TEST $CLI volume create $V0 $H0:$B0/${V0}1;
+
+function volinfo_field()
+{
+    local vol=$1;
+    local field=$2;
+
+    $CLI volume info $vol | grep "^$field: " | sed 's/.*: //';
+}
+
+
+## Verify volume is is created
+EXPECT "$V0" volinfo_field $V0 'Volume Name';
+EXPECT 'Created' volinfo_field $V0 'Status';
+
+
+## Start volume and verify
+TEST $CLI volume start $V0;
+EXPECT 'Started' volinfo_field $V0 'Status';
+
+
+## Make volume tightly consistent for metdata
+TEST $CLI volume set $V0 performance.stat-prefetch off;
+
+## Mount FUSE with caching disabled
+TEST glusterfs --entry-timeout=0 --attribute-timeout=0 -s $H0 --volfile-id $V0 $M0;
+
+function cleanup_tester ()
+{
+    local exe=$1
+    rm -f $exe
+}
+
+function build_tester ()
+{
+    local cfile=$1
+    local fname=$(basename "$cfile")
+    local ext="${fname##*.}"
+    local execname="${fname%.*}"
+    gcc -g -o $(dirname $cfile)/$execname $cfile
+}
+
+touch $M0/test;
+build_tester $(dirname $0)/getlk_owner.c
+
+TEST $(dirname $0)/getlk_owner $M0/test;
+
+rm -f $(dirname $0)/getlk_owner
+cleanup;
+

tests/bugs/getlk_owner.c

@@ -0,0 +1,120 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <string.h>
+
+#define GETLK_OWNER_CHECK(f, cp, label)                     \
+    do {                                                    \
+        switch (f.l_type) {                                 \
+            case F_RDLCK:                                   \
+            case F_WRLCK:                                   \
+                ret = 1;                                    \
+                goto label;                                 \
+            case F_UNLCK:                                   \
+                if (!are_flocks_sane (&f, &cp)) {           \
+                    ret = 1;                                \
+                    goto label;                             \
+                }                                           \
+                break;                                      \
+        }                                                   \
+    } while (0)
+
+void
+flock_init (struct flock *f, short int type, off_t start, off_t len)
+{
+    f->l_type = type;
+    f->l_start = start;
+    f->l_len = len;
+}
+
+int
+flock_cp (struct flock *dst, struct flock *src)
+{
+    memcpy ((void *) dst, (void *) src, sizeof (struct flock));
+}
+
+int
+are_flocks_sane (struct flock *src, struct flock *cpy)
+{
+    return ((src->l_whence == cpy->l_whence) &&
+            (src->l_start == cpy->l_start) &&
+            (src->l_len == cpy->l_len));
+}
+
+/*
+ * Test description:
+ * SETLK (0,3), F_WRLCK
+ * SETLK (3,3), F_WRLCK
+ *
+ * the following GETLK requests must return flock struct unmodified
+ * except for l_type to F_UNLCK
+ * GETLK (3,3), F_WRLCK
+ * GETLK (3,3), F_RDLCK
+ *
+ * */
+
+int main (int argc, char **argv)
+{
+    int fd = -1;
+    int ret = 1;
+    char *fname = NULL;
+    struct flock f = {0,};
+    struct flock cp = {0,};
+
+    if (argc < 2)
+        goto out;
+
+    fname = argv[1];
+    fd = open (fname, O_RDWR);
+    if (fd == -1) {
+        perror ("open");
+        goto out;
+    }
+
+    flock_init (&f, F_WRLCK, 0, 3);
+    flock_cp (&cp, &f);
+    ret = fcntl (fd, F_SETLK, &f);
+    if (ret) {
+        perror ("fcntl");
+        goto out;
+    }
+    if (!are_flocks_sane (&f, &cp)) {
+        ret = 1;
+        goto out;
+    }
+
+    flock_init (&f, F_WRLCK, 3, 3);
+    flock_cp (&cp, &f);
+    ret = fcntl (fd, F_SETLK, &f);
+    if (ret) {
+        perror ("fcntl");
+        goto out;
+    }
+    if (!are_flocks_sane (&f, &cp)) {
+        ret = 1;
+        goto out;
+    }
+
+    flock_init (&f, F_WRLCK, 3, 3);
+    flock_cp (&cp, &f);
+    ret = fcntl (fd, F_GETLK, &f);
+    if (ret) {
+        perror ("fcntl");
+        return 1;
+    }
+    GETLK_OWNER_CHECK (f, cp, out);
+
+    flock_init (&f, F_RDLCK, 3, 3);
+    flock_cp (&cp, &f);
+    ret = fcntl (fd, F_GETLK, &f);
+    if (ret) {
+        perror ("fcntl");
+        return 1;
+    }
+    GETLK_OWNER_CHECK (f, cp, out);
+
+out:
+    if (fd != -1)
+        close (fd);
+    return ret;
+}

xlators/features/locks/src/common.c

@@ -714,6 +714,28 @@ done:
         return v;
 }
 
+static posix_lock_t *
+first_conflicting_overlap (pl_inode_t *pl_inode, posix_lock_t *lock)
+{
+        posix_lock_t *l = NULL;
+
+        list_for_each_entry (l, &pl_inode->ext_list, list) {
+                if (l->blocked)
+                        continue;
+
+                if (locks_overlap (l, lock)) {
+                        if (same_owner (l, lock))
+                                continue;
+
+                        if ((l->fl_type == F_WRLCK) ||
+                            (lock->fl_type == F_WRLCK))
+                                return l;
+                }
+        }
+
+        return NULL;
+}
+
 /*
   Start searching from {begin}, and return the first lock that
   conflicts, NULL if no conflict
@@ -1058,7 +1080,7 @@ pl_getlk (pl_inode_t *pl_inode, posix_lock_t *lock)
 {
         posix_lock_t *conf = NULL;
 
-        conf = first_overlap (pl_inode, lock);
+        conf = first_conflicting_overlap (pl_inode, lock);
 
         if (conf == NULL) {
                 lock->fl_type = F_UNLCK;