10:53 a.m.
Gitweb:
http://git.fedorahosted.org/git/cluster.git?p=cluster.git;a=commitdiff;h=...
Commit: bc271e80a8221d264d269a74ccf6e46c4b6cce4d
Parent: 04f7da379c163876eb346f3828de0ff152e25f5a
Author: Abhijith Das <adas(a)redhat.com>
AuthorDate: Thu Feb 11 10:48:24 2010 -0600
Committer: Abhijith Das <adas(a)redhat.com>
CommitterDate: Thu Feb 11 10:52:23 2010 -0600
gfs-kernel: Flock on GFS fs file will error with "Resource tempory unavailable"
for EWOULDBLOCK
This patch allows a process to queue multiple flocks
through multiple descriptors and the behavior is similar
to that of GFS2. This patch also eliminates the race
condition involving a single process where a holder from
a previous unlock that has still not completely been
dequeued prevents a subsequent non-blocking flock from
going through and instead returns EAGAIN. This patch will
cause the non-blocking request to block until the
aforementioned unlock holder has been cleared.
rhbz#515717
---
gfs-kernel/src/gfs/glock.c | 74 +++++++++++++++++++++++++++++++----------
gfs-kernel/src/gfs/glock.h | 2 +
gfs-kernel/src/gfs/incore.h | 2 +
gfs-kernel/src/gfs/ops_file.c | 15 ++++----
4 files changed, 67 insertions(+), 26 deletions(-)
diff --git a/gfs-kernel/src/gfs/glock.c b/gfs-kernel/src/gfs/glock.c
index 3040c60..80f4466 100644
--- a/gfs-kernel/src/gfs/glock.c
+++ b/gfs-kernel/src/gfs/glock.c
@@ -986,6 +986,33 @@ state_change(struct gfs_glock *gl, unsigned int new_state)
gl->gl_state = new_state;
}
+static int gfs_glock_demote_wait(void *word)
+{
+ schedule();
+ return 0;
+}
+
+static void gfs_wait_on_demote(struct gfs_glock *gl)
+{
+ might_sleep();
+ wait_on_bit(&gl->gl_flags, GLF_DEMOTE, gfs_glock_demote_wait,
TASK_UNINTERRUPTIBLE);
+}
+
+static void gfs_demote_wake(struct gfs_glock *gl)
+{
+ clear_bit(GLF_DEMOTE, &gl->gl_flags);
+ smp_mb__after_clear_bit();
+ wake_up_bit(&gl->gl_flags, GLF_DEMOTE);
+}
+
+void gfs_glock_dq_wait(struct gfs_holder *gh)
+{
+ struct gfs_glock *gl = gh->gh_gl;
+ set_bit(GLF_DEMOTE, &gl->gl_flags);
+ gfs_glock_dq(gh);
+ gfs_wait_on_demote(gl);
+}
+
/**
* xmote_bh - Called after the lock module is done acquiring a lock
* @gl: The glock in question
@@ -1091,6 +1118,8 @@ xmote_bh(struct gfs_glock *gl, unsigned int ret)
gl->gl_req_bh = NULL;
clear_bit(GLF_LOCK, &gl->gl_flags);
run_queue(gl);
+ if (test_bit(GLF_DEMOTE, &gl->gl_flags))
+ gfs_demote_wake(gl);
spin_unlock(&gl->gl_spin);
}
@@ -1200,8 +1229,9 @@ drop_bh(struct gfs_glock *gl, unsigned int ret)
gl->gl_req_bh = NULL;
clear_bit(GLF_LOCK, &gl->gl_flags);
run_queue(gl);
- spin_unlock(&gl->gl_spin);
-
+ if (test_bit(GLF_DEMOTE, &gl->gl_flags))
+ gfs_demote_wake(gl);
+ spin_unlock(&gl->gl_spin);
glock_put(gl);
if (gh) {
@@ -1312,6 +1342,11 @@ glock_wait_internal(struct gfs_holder *gh)
if (gl->gl_req_gh != gh &&
!test_bit(HIF_HOLDER, &gh->gh_iflags) &&
!list_empty(&gh->gh_list)) {
+ if (gh->gh_flags & GL_FLOCK &&
+ list_empty(&gl->gl_holders)) {
+ spin_unlock(&gl->gl_spin);
+ goto skip_try_flag;
+ }
list_del_init(&gh->gh_list);
gh->gh_error = GLR_TRYFAILED;
if (test_bit(HIF_RECURSE, &gh->gh_iflags))
@@ -1323,6 +1358,7 @@ glock_wait_internal(struct gfs_holder *gh)
spin_unlock(&gl->gl_spin);
}
+skip_try_flag:
if ((gh->gh_flags & LM_FLAG_PRIORITY) &&
!(gh->gh_flags & GL_NOCANCEL_OTHER))
do_cancels(gh);
@@ -1402,13 +1438,14 @@ add_to_queue(struct gfs_holder *gh)
if (tmp_gh->gh_owner == gh->gh_owner) {
/* Make sure pre-existing holder is compatible
with this new one. */
- if (gfs_assert_warn(sdp, (gh->gh_flags & LM_FLAG_ANY) ||
- !(tmp_gh->gh_flags & LM_FLAG_ANY)) ||
- gfs_assert_warn(sdp, (tmp_gh->gh_flags & GL_LOCAL_EXCL) ||
- !(gh->gh_flags & GL_LOCAL_EXCL)) ||
- gfs_assert_warn(sdp, relaxed_state_ok(gl->gl_state,
- gh->gh_state,
- gh->gh_flags)))
+ if (!(gh->gh_flags & GL_FLOCK) &&
+ (gfs_assert_warn(sdp, (gh->gh_flags & LM_FLAG_ANY) ||
+ !(tmp_gh->gh_flags & LM_FLAG_ANY)) ||
+ gfs_assert_warn(sdp, (tmp_gh->gh_flags & GL_LOCAL_EXCL) ||
+ !(gh->gh_flags & GL_LOCAL_EXCL)) ||
+ gfs_assert_warn(sdp, relaxed_state_ok(gl->gl_state,
+ gh->gh_state,
+ gh->gh_flags))))
goto fail;
/* We're good! Grant the hold. */
@@ -1430,15 +1467,16 @@ add_to_queue(struct gfs_holder *gh)
tmp_gh = list_entry(tmp, struct gfs_holder, gh_list);
if (tmp_gh->gh_owner == gh->gh_owner) {
/* Yes, make sure it is compatible with new */
- if (gfs_assert_warn(sdp, test_bit(HIF_PROMOTE,
- &tmp_gh->gh_iflags)) ||
- gfs_assert_warn(sdp, (gh->gh_flags & LM_FLAG_ANY) ||
- !(tmp_gh->gh_flags & LM_FLAG_ANY)) ||
- gfs_assert_warn(sdp, (tmp_gh->gh_flags & GL_LOCAL_EXCL) ||
- !(gh->gh_flags & GL_LOCAL_EXCL)) ||
- gfs_assert_warn(sdp, relaxed_state_ok(tmp_gh->gh_state,
- gh->gh_state,
- gh->gh_flags)))
+ if (!(gh->gh_flags & GL_FLOCK) &&
+ (gfs_assert_warn(sdp, test_bit(HIF_PROMOTE,
+ &tmp_gh->gh_iflags)) ||
+ gfs_assert_warn(sdp, (gh->gh_flags & LM_FLAG_ANY) ||
+ !(tmp_gh->gh_flags & LM_FLAG_ANY)) ||
+ gfs_assert_warn(sdp, (tmp_gh->gh_flags & GL_LOCAL_EXCL) ||
+ !(gh->gh_flags & GL_LOCAL_EXCL)) ||
+ gfs_assert_warn(sdp, relaxed_state_ok(tmp_gh->gh_state,
+ gh->gh_state,
+ gh->gh_flags))))
goto fail;
/* OK, make sure they're marked, so
diff --git a/gfs-kernel/src/gfs/glock.h b/gfs-kernel/src/gfs/glock.h
index a0342b1..9de5e94 100644
--- a/gfs-kernel/src/gfs/glock.h
+++ b/gfs-kernel/src/gfs/glock.h
@@ -21,6 +21,7 @@
#define GL_SYNC (0x00000800) /* Sync to disk when no more holders */
#define GL_NOCANCEL (0x00001000) /* Don't ever cancel this request */
#define GL_NOCANCEL_OTHER (0x00004000) /* Don't cancel other locks for this */
+#define GL_FLOCK (0x00008000) /* This is an flock */
#define GLR_TRYFAILED (13)
#define GLR_CANCELED (14)
@@ -96,6 +97,7 @@ int gfs_glock_nq(struct gfs_holder *gh);
int gfs_glock_poll(struct gfs_holder *gh);
int gfs_glock_wait(struct gfs_holder *gh);
void gfs_glock_dq(struct gfs_holder *gh);
+void gfs_glock_dq_wait(struct gfs_holder *gh);
void gfs_glock_prefetch(struct gfs_glock *gl, unsigned int state, int flags);
void gfs_glock_force_drop(struct gfs_glock *gl);
diff --git a/gfs-kernel/src/gfs/incore.h b/gfs-kernel/src/gfs/incore.h
index 1e00fc2..921b79d 100644
--- a/gfs-kernel/src/gfs/incore.h
+++ b/gfs-kernel/src/gfs/incore.h
@@ -474,6 +474,8 @@ struct gfs_holder {
* (demote/greedy) holders */
#define GLF_GREEDY (7) /* This lock is ignoring callbacks
* (requests from other nodes) for now */
+#define GLF_DEMOTE (8) /* This is used to check for unflock completion
+ * different from HIF_DEMOTE */
struct gfs_glock {
struct list_head gl_list; /* Link to hb_list in one of superblock's
diff --git a/gfs-kernel/src/gfs/ops_file.c b/gfs-kernel/src/gfs/ops_file.c
index 6a64958..e675772 100644
--- a/gfs-kernel/src/gfs/ops_file.c
+++ b/gfs-kernel/src/gfs/ops_file.c
@@ -1732,7 +1732,8 @@ do_flock(struct file *file, int cmd, struct file_lock *fl)
int error = 0;
state = (fl->fl_type == F_WRLCK) ? LM_ST_EXCLUSIVE : LM_ST_SHARED;
- flags = ((IS_SETLKW(cmd)) ? 0 : LM_FLAG_TRY) | GL_EXACT | GL_NOCACHE;
+ flags = ((IS_SETLKW(cmd)) ? 0 : LM_FLAG_TRY) | GL_EXACT | GL_NOCACHE
+ | GL_FLOCK;
down(&fp->f_fl_lock);
@@ -1740,21 +1741,19 @@ do_flock(struct file *file, int cmd, struct file_lock *fl)
if (gl) {
if (fl_gh->gh_state == state)
goto out;
- gfs_glock_hold(gl);
flock_lock_file_wait(file,
- &(struct file_lock){.fl_type = F_UNLCK});
- gfs_glock_dq_uninit(fl_gh);
+ &(struct file_lock){.fl_type = F_UNLCK});
+ gfs_glock_dq_wait(fl_gh);
+ gfs_holder_reinit(state, flags, fl_gh);
} else {
error = gfs_glock_get(ip->i_sbd,
ip->i_num.no_formal_ino, &gfs_flock_glops,
CREATE, &gl);
if (error)
goto out;
+ gfs_holder_init(gl, state, flags, fl_gh);
+ gfs_glock_put(gl);
}
-
- gfs_holder_init(gl, state, flags, fl_gh);
- gfs_glock_put(gl);
-
error = gfs_glock_nq(fl_gh);
if (error) {
gfs_holder_uninit(fl_gh);