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[GFS2] Don't do recursive locking in glock layer
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This patch changes the last user of recursive locking so that
it no longer needs this feature and removes it from the glock
layer. This makes the glock code a lot simpler and easier to
understand. Its also a prerequsite to adding support for the
AOP_TRUNCATED_PAGE return code (or at least it is if you don't
want your brain to melt in the process)

I've left in a couple of checks just in case there is some place
else in the code which is still using this feature that I didn't
spot yet, but they can probably be removed long term.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
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Steven Whitehouse committed Apr 26, 2006
1 parent 3a2a9c9 commit 5965b1f
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Showing 3 changed files with 46 additions and 196 deletions.
162 changes: 6 additions & 156 deletions fs/gfs2/glock.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -449,86 +449,6 @@ void gfs2_holder_put(struct gfs2_holder *gh)
kfree(gh);
}

/**
* handle_recurse - put other holder structures (marked recursive)
* into the holders list
* @gh: the holder structure
*
*/

static void handle_recurse(struct gfs2_holder *gh)
{
struct gfs2_glock *gl = gh->gh_gl;
struct gfs2_sbd *sdp = gl->gl_sbd;
struct gfs2_holder *tmp_gh, *safe;
int found = 0;

BUG_ON(!spin_is_locked(&gl->gl_spin));

printk(KERN_INFO "recursion %016llx, %u\n", gl->gl_name.ln_number,
gl->gl_name.ln_type);

if (gfs2_assert_warn(sdp, gh->gh_owner))
return;

list_for_each_entry_safe(tmp_gh, safe, &gl->gl_waiters3, gh_list) {
if (tmp_gh->gh_owner != gh->gh_owner)
continue;

gfs2_assert_warn(sdp,
test_bit(HIF_RECURSE, &tmp_gh->gh_iflags));

list_move_tail(&tmp_gh->gh_list, &gl->gl_holders);
tmp_gh->gh_error = 0;
set_bit(HIF_HOLDER, &tmp_gh->gh_iflags);

complete(&tmp_gh->gh_wait);

found = 1;
}

gfs2_assert_warn(sdp, found);
}

/**
* do_unrecurse - a recursive holder was just dropped of the waiters3 list
* @gh: the holder
*
* If there is only one other recursive holder, clear its HIF_RECURSE bit.
* If there is more than one, leave them alone.
*
*/

static void do_unrecurse(struct gfs2_holder *gh)
{
struct gfs2_glock *gl = gh->gh_gl;
struct gfs2_sbd *sdp = gl->gl_sbd;
struct gfs2_holder *tmp_gh, *last_gh = NULL;
int found = 0;

BUG_ON(!spin_is_locked(&gl->gl_spin));

if (gfs2_assert_warn(sdp, gh->gh_owner))
return;

list_for_each_entry(tmp_gh, &gl->gl_waiters3, gh_list) {
if (tmp_gh->gh_owner != gh->gh_owner)
continue;

gfs2_assert_warn(sdp,
test_bit(HIF_RECURSE, &tmp_gh->gh_iflags));

if (found)
return;

found = 1;
last_gh = tmp_gh;
}

if (!gfs2_assert_warn(sdp, found))
clear_bit(HIF_RECURSE, &last_gh->gh_iflags);
}

/**
* rq_mutex - process a mutex request in the queue
* @gh: the glock holder
Expand Down Expand Up @@ -562,7 +482,6 @@ static int rq_promote(struct gfs2_holder *gh)
struct gfs2_glock *gl = gh->gh_gl;
struct gfs2_sbd *sdp = gl->gl_sbd;
struct gfs2_glock_operations *glops = gl->gl_ops;
int recurse;

if (!relaxed_state_ok(gl->gl_state, gh->gh_state, gh->gh_flags)) {
if (list_empty(&gl->gl_holders)) {
Expand All @@ -588,7 +507,6 @@ static int rq_promote(struct gfs2_holder *gh)
if (list_empty(&gl->gl_holders)) {
set_bit(HIF_FIRST, &gh->gh_iflags);
set_bit(GLF_LOCK, &gl->gl_flags);
recurse = 0;
} else {
struct gfs2_holder *next_gh;
if (gh->gh_flags & GL_LOCAL_EXCL)
Expand All @@ -597,16 +515,12 @@ static int rq_promote(struct gfs2_holder *gh)
gh_list);
if (next_gh->gh_flags & GL_LOCAL_EXCL)
return 1;
recurse = test_bit(HIF_RECURSE, &gh->gh_iflags);
}

list_move_tail(&gh->gh_list, &gl->gl_holders);
gh->gh_error = 0;
set_bit(HIF_HOLDER, &gh->gh_iflags);

if (recurse)
handle_recurse(gh);

complete(&gh->gh_wait);

return 0;
Expand Down Expand Up @@ -897,8 +811,6 @@ static void xmote_bh(struct gfs2_glock *gl, unsigned int ret)
spin_lock(&gl->gl_spin);
list_del_init(&gh->gh_list);
gh->gh_error = -EIO;
if (test_bit(HIF_RECURSE, &gh->gh_iflags))
do_unrecurse(gh);
spin_unlock(&gl->gl_spin);

} else if (test_bit(HIF_DEMOTE, &gh->gh_iflags)) {
Expand All @@ -922,8 +834,6 @@ static void xmote_bh(struct gfs2_glock *gl, unsigned int ret)
spin_lock(&gl->gl_spin);
list_del_init(&gh->gh_list);
gh->gh_error = GLR_CANCELED;
if (test_bit(HIF_RECURSE, &gh->gh_iflags))
do_unrecurse(gh);
spin_unlock(&gl->gl_spin);

} else if (relaxed_state_ok(gl->gl_state, gh->gh_state, gh->gh_flags)) {
Expand All @@ -941,8 +851,6 @@ static void xmote_bh(struct gfs2_glock *gl, unsigned int ret)
spin_lock(&gl->gl_spin);
list_del_init(&gh->gh_list);
gh->gh_error = GLR_TRYFAILED;
if (test_bit(HIF_RECURSE, &gh->gh_iflags))
do_unrecurse(gh);
spin_unlock(&gl->gl_spin);

} else {
Expand Down Expand Up @@ -1161,8 +1069,6 @@ static int glock_wait_internal(struct gfs2_holder *gh)
!list_empty(&gh->gh_list)) {
list_del_init(&gh->gh_list);
gh->gh_error = GLR_TRYFAILED;
if (test_bit(HIF_RECURSE, &gh->gh_iflags))
do_unrecurse(gh);
run_queue(gl);
spin_unlock(&gl->gl_spin);
return gh->gh_error;
Expand Down Expand Up @@ -1191,9 +1097,6 @@ static int glock_wait_internal(struct gfs2_holder *gh)
if (gh->gh_error) {
spin_lock(&gl->gl_spin);
list_del_init(&gh->gh_list);
if (test_and_clear_bit(HIF_RECURSE,
&gh->gh_iflags))
do_unrecurse(gh);
spin_unlock(&gl->gl_spin);
}
}
Expand All @@ -1202,8 +1105,6 @@ static int glock_wait_internal(struct gfs2_holder *gh)
gl->gl_req_gh = NULL;
gl->gl_req_bh = NULL;
clear_bit(GLF_LOCK, &gl->gl_flags);
if (test_bit(HIF_RECURSE, &gh->gh_iflags))
handle_recurse(gh);
run_queue(gl);
spin_unlock(&gl->gl_spin);
}
Expand All @@ -1224,40 +1125,6 @@ find_holder_by_owner(struct list_head *head, struct task_struct *owner)
return NULL;
}

/**
* recurse_check -
*
* Make sure the new holder is compatible with the pre-existing one.
*
*/

static int recurse_check(struct gfs2_holder *existing, struct gfs2_holder *new,
unsigned int state)
{
struct gfs2_sbd *sdp = existing->gh_gl->gl_sbd;

if (gfs2_assert_warn(sdp, (new->gh_flags & LM_FLAG_ANY) ||
!(existing->gh_flags & LM_FLAG_ANY)))
goto fail;

if (gfs2_assert_warn(sdp, (existing->gh_flags & GL_LOCAL_EXCL) ||
!(new->gh_flags & GL_LOCAL_EXCL)))
goto fail;

if (gfs2_assert_warn(sdp, relaxed_state_ok(state, new->gh_state,
new->gh_flags)))
goto fail;

return 0;

fail:
print_symbol(KERN_WARNING "GFS2: Existing holder from %s\n",
existing->gh_ip);
print_symbol(KERN_WARNING "GFS2: New holder from %s\n", new->gh_ip);
set_bit(HIF_ABORTED, &new->gh_iflags);
return -EINVAL;
}

/**
* add_to_queue - Add a holder to the wait queue (but look for recursion)
* @gh: the holder structure to add
Expand All @@ -1271,37 +1138,20 @@ static void add_to_queue(struct gfs2_holder *gh)

BUG_ON(!gh->gh_owner);

if (!gh->gh_owner)
goto out;

existing = find_holder_by_owner(&gl->gl_holders, gh->gh_owner);
if (existing) {
if (recurse_check(existing, gh, gl->gl_state))
return;

list_add_tail(&gh->gh_list, &gl->gl_holders);
set_bit(HIF_HOLDER, &gh->gh_iflags);

gh->gh_error = 0;
complete(&gh->gh_wait);

return;
print_symbol(KERN_WARNING "original: %s\n", existing->gh_ip);
print_symbol(KERN_WARNING "new: %s\n", gh->gh_ip);
BUG();
}

existing = find_holder_by_owner(&gl->gl_waiters3, gh->gh_owner);
if (existing) {
if (recurse_check(existing, gh, existing->gh_state))
return;

set_bit(HIF_RECURSE, &gh->gh_iflags);
set_bit(HIF_RECURSE, &existing->gh_iflags);

list_add_tail(&gh->gh_list, &gl->gl_waiters3);

return;
print_symbol(KERN_WARNING "original: %s\n", existing->gh_ip);
print_symbol(KERN_WARNING "new: %s\n", gh->gh_ip);
BUG();
}

out:
if (gh->gh_flags & LM_FLAG_PRIORITY)
list_add(&gh->gh_list, &gl->gl_waiters3);
else
Expand Down
1 change: 0 additions & 1 deletion fs/gfs2/incore.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -146,7 +146,6 @@ enum {
HIF_DEALLOC = 5,
HIF_HOLDER = 6,
HIF_FIRST = 7,
HIF_RECURSE = 8,
HIF_ABORTED = 9,
};

Expand Down
79 changes: 40 additions & 39 deletions fs/gfs2/recovery.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -436,30 +436,35 @@ int gfs2_recover_journal(struct gfs2_jdesc *jd)
unsigned int pass;
int error;

fs_info(sdp, "jid=%u: Trying to acquire journal lock...\n", jd->jd_jid);

/* Aquire the journal lock so we can do recovery */

error = gfs2_glock_nq_num(sdp, jd->jd_jid, &gfs2_journal_glops,
LM_ST_EXCLUSIVE,
LM_FLAG_NOEXP | LM_FLAG_TRY | GL_NOCACHE,
&j_gh);
switch (error) {
case 0:
break;
if (jd->jd_jid != sdp->sd_lockstruct.ls_jid) {
fs_info(sdp, "jid=%u: Trying to acquire journal lock...\n",
jd->jd_jid);

case GLR_TRYFAILED:
fs_info(sdp, "jid=%u: Busy\n", jd->jd_jid);
error = 0;
/* Aquire the journal lock so we can do recovery */

default:
goto fail;
};
error = gfs2_glock_nq_num(sdp, jd->jd_jid, &gfs2_journal_glops,
LM_ST_EXCLUSIVE,
LM_FLAG_NOEXP | LM_FLAG_TRY | GL_NOCACHE,
&j_gh);
switch (error) {
case 0:
break;

case GLR_TRYFAILED:
fs_info(sdp, "jid=%u: Busy\n", jd->jd_jid);
error = 0;

default:
goto fail;
};

error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED,
LM_FLAG_NOEXP, &ji_gh);
if (error)
goto fail_gunlock_j;
error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED,
LM_FLAG_NOEXP, &ji_gh);
if (error)
goto fail_gunlock_j;
} else {
fs_info(sdp, "jid=%u, already locked for use\n", jd->jd_jid);
}

fs_info(sdp, "jid=%u: Looking at journal...\n", jd->jd_jid);

Expand All @@ -481,10 +486,8 @@ int gfs2_recover_journal(struct gfs2_jdesc *jd)

error = gfs2_glock_nq_init(sdp->sd_trans_gl,
LM_ST_SHARED,
LM_FLAG_NOEXP |
LM_FLAG_PRIORITY |
GL_NEVER_RECURSE |
GL_NOCANCEL |
LM_FLAG_NOEXP | LM_FLAG_PRIORITY |
GL_NEVER_RECURSE | GL_NOCANCEL |
GL_NOCACHE,
&t_gh);
if (error)
Expand Down Expand Up @@ -521,37 +524,35 @@ int gfs2_recover_journal(struct gfs2_jdesc *jd)
goto fail_gunlock_tr;

gfs2_glock_dq_uninit(&t_gh);

t = DIV_ROUND_UP(jiffies - t, HZ);

fs_info(sdp, "jid=%u: Journal replayed in %lus\n",
jd->jd_jid, t);
}

gfs2_glock_dq_uninit(&ji_gh);
if (jd->jd_jid != sdp->sd_lockstruct.ls_jid)
gfs2_glock_dq_uninit(&ji_gh);

gfs2_lm_recovery_done(sdp, jd->jd_jid, LM_RD_SUCCESS);

gfs2_glock_dq_uninit(&j_gh);
if (jd->jd_jid != sdp->sd_lockstruct.ls_jid)
gfs2_glock_dq_uninit(&j_gh);

fs_info(sdp, "jid=%u: Done\n", jd->jd_jid);

return 0;

fail_gunlock_tr:
fail_gunlock_tr:
gfs2_glock_dq_uninit(&t_gh);

fail_gunlock_ji:
gfs2_glock_dq_uninit(&ji_gh);

fail_gunlock_j:
gfs2_glock_dq_uninit(&j_gh);
fail_gunlock_ji:
if (jd->jd_jid != sdp->sd_lockstruct.ls_jid) {
gfs2_glock_dq_uninit(&ji_gh);
fail_gunlock_j:
gfs2_glock_dq_uninit(&j_gh);
}

fs_info(sdp, "jid=%u: %s\n", jd->jd_jid, (error) ? "Failed" : "Done");

fail:
fail:
gfs2_lm_recovery_done(sdp, jd->jd_jid, LM_RD_GAVEUP);

return error;
}

Expand Down

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