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- serialize BDB environment open/close (#924417)

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This commit is contained in:
Panu Matilainen 2013-05-28 09:38:53 +03:00
parent 1cefad535c
commit e033e9868a
2 changed files with 145 additions and 1 deletions
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138
rpm-4.11.x-dbenv-serialize.patch Normal file
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@ -0,0 +1,138 @@
commit e7d5980e2a7b091d973171144de04397204ebcd7
Author: Panu Matilainen <pmatilai@redhat.com>
Date: Tue May 28 08:56:22 2013 +0300
Serialize BDB environment open/close (RhBug:924417 etc)
- Introduce Yet Another Broken Lock[*] to serialize BDB environment open:
otherwise we can end up calling dbenv->failchk() while another process
is just joining the environment, leading to transient "Thread died in..."
DB_RUNRECOVER errors. Also prevents races on chrooted operations where
we remove the entire environment on close.
- This should also make it possible to handle at least some cases of
real DB_RUNRECOVER errors by just nuking the environment but that's
another topic...
[*] YABL as this is nowhere near foolproof or sufficient for all
the possible variants, but better than not having it...
(cherry picked from commit ad874d60e3804f1bcd64f3510e1e2dfbf81456cd)
diff --git a/lib/backend/db3.c b/lib/backend/db3.c
index de8071b..9d385c6 100644
--- a/lib/backend/db3.c
+++ b/lib/backend/db3.c
@@ -57,10 +57,42 @@ static uint32_t db_envflags(DB * db)
return eflags;
}
+/*
+ * Try to acquire db environment open/close serialization lock.
+ * Return the open, locked fd on success, -1 on failure.
+ */
+static int serialize_env(const char *dbhome)
+{
+ char *lock_path = rstrscat(NULL, dbhome, "/.dbenv.lock", NULL);
+ mode_t oldmask = umask(022);
+ int fd = open(lock_path, (O_RDWR|O_CREAT), 0644);
+ umask(oldmask);
+
+ if (fd >= 0) {
+ int rc;
+ struct flock info;
+ memset(&info, 0, sizeof(info));
+ info.l_type = F_WRLCK;
+ info.l_whence = SEEK_SET;
+ do {
+ rc = fcntl(fd, F_SETLKW, &info);
+ } while (rc == -1 && errno == EINTR);
+
+ if (rc == -1) {
+ close(fd);
+ fd = -1;
+ }
+ }
+
+ free(lock_path);
+ return fd;
+}
+
static int db_fini(rpmdb rdb, const char * dbhome)
{
DB_ENV * dbenv = rdb->db_dbenv;
int rc;
+ int lockfd = -1;
uint32_t eflags = 0;
if (dbenv == NULL)
@@ -72,6 +104,9 @@ static int db_fini(rpmdb rdb, const char * dbhome)
}
(void) dbenv->get_open_flags(dbenv, &eflags);
+ if (!(eflags & DB_PRIVATE))
+ lockfd = serialize_env(dbhome);
+
rc = dbenv->close(dbenv, 0);
rc = dbapi_err(rdb, "dbenv->close", rc, _debug);
@@ -89,6 +124,10 @@ static int db_fini(rpmdb rdb, const char * dbhome)
rpmlog(RPMLOG_DEBUG, "removed db environment %s\n", dbhome);
}
+
+ if (lockfd >= 0)
+ close(lockfd);
+
return rc;
}
@@ -122,6 +161,7 @@ static int db_init(rpmdb rdb, const char * dbhome)
DB_ENV *dbenv = NULL;
int rc, xx;
int retry_open = 2;
+ int lockfd = -1;
struct dbConfig_s * cfg = &rdb->cfg;
/* This is our setup, thou shall not have other setups before us */
uint32_t eflags = (DB_CREATE|DB_INIT_MPOOL|DB_INIT_CDB);
@@ -176,6 +216,24 @@ static int db_init(rpmdb rdb, const char * dbhome)
}
/*
+ * Serialize shared environment open (and clock) via fcntl() lock.
+ * Otherwise we can end up calling dbenv->failchk() while another
+ * process is joining the environment, leading to transient
+ * DB_RUNRECOVER errors. Also prevents races wrt removing the
+ * environment (eg chrooted operation). Silently fall back to
+ * private environment on failure to allow non-privileged queries
+ * to "work", broken as it might be.
+ */
+ if (!(eflags & DB_PRIVATE)) {
+ lockfd = serialize_env(dbhome);
+ if (lockfd < 0) {
+ eflags |= DB_PRIVATE;
+ retry_open--;
+ rpmlog(RPMLOG_DEBUG, "serialize failed, using private dbenv\n");
+ }
+ }
+
+ /*
* Actually open the environment. Fall back to private environment
* if we dont have permission to join/create shared environment or
* system doesn't support it..
@@ -208,6 +266,8 @@ static int db_init(rpmdb rdb, const char * dbhome)
rdb->db_dbenv = dbenv;
rdb->db_opens = 1;
+ if (lockfd >= 0)
+ close(lockfd);
return 0;
errxit:
@@ -216,6 +276,8 @@ errxit:
xx = dbenv->close(dbenv, 0);
xx = dbapi_err(rdb, "dbenv->close", xx, _debug);
}
+ if (lockfd >= 0)
+ close(lockfd);
return rc;
}

8
rpm.spec
View File

@ -21,7 +21,7 @@
Summary: The RPM package management system
Name: rpm
Version: %{rpmver}
Release: %{?snapver:0.%{snapver}.}6%{?dist}
Release: %{?snapver:0.%{snapver}.}7%{?dist}
Group: System Environment/Base
Url: http://www.rpm.org/
Source0: http://rpm.org/releases/testing/%{name}-%{srcver}.tar.bz2
@ -53,6 +53,8 @@ Patch101: rpm-4.11.x-cursor-failchk.patch
Patch102: rpm-4.11.x-filter-soname-deps.patch
# Stricter perllib classification
Patch103: rpm-4.11.x-perllib-attr.patch
# Serialize BDB environment open+close
Patch104: rpm-4.11.x-dbenv-serialize.patch
# These are not yet upstream
Patch301: rpm-4.6.0-niagara.patch
@ -235,6 +237,7 @@ packages on a system.
%patch101 -p1 -b .cursor-failchk
%patch102 -p1 -b .filter-soname-deps
%patch103 -p1 -b .perllib-attr
%patch104 -p1 -b .dbenv-serialize
%patch301 -p1 -b .niagara
%patch302 -p1 -b .geode
@ -468,6 +471,9 @@ exit 0
%doc COPYING doc/librpm/html/*
%changelog
* Tue May 28 2013 Panu Matilainen <pmatilai@redhat.com> - - 4.11.0.1-7
- serialize BDB environment open/close (#924417)
* Wed May 22 2013 Panu Matilainen <pmatilai@redhat.com> - - 4.11.0.1-6
- only consider files with .pm suffix as perl modules (#927211)