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| author | Bob Peterson <rpeterso@redhat.com> | 2019-11-15 18:45:41 +0300 |
|---|---|---|
| committer | Andreas Gruenbacher <agruenba@redhat.com> | 2019-11-15 20:21:59 +0300 |
| commit | d99724c3c36ae73ed3908f5e3f2d103a48cd9ad0 (patch) | |
| tree | 9c6ced7bd5fc803ca864c78ee981ea305e9c4c39 /fs/gfs2 | |
| parent | 52b1cdcb7a84a4a3cec0093eaf390bf2e11e4278 (diff) | |
| download | linux-d99724c3c36ae73ed3908f5e3f2d103a48cd9ad0.tar.xz | |
gfs2: Close timing window with GLF_INVALIDATE_IN_PROGRESS
This patch closes a timing window in which two processes compete
and overlap in the execution of do_xmote for the same glock:
Process A Process B
------------------------------------ -----------------------------
1. Grabs gl_lockref and calls do_xmote
2. Grabs gl_lockref but is blocked
3. Sets GLF_INVALIDATE_IN_PROGRESS
4. Unlocks gl_lockref
5. Calls do_xmote
6. Call glops->go_sync
7. test_and_clear_bit GLF_DIRTY
8. Call gfs2_log_flush Call glops->go_sync
9. (slow IO, so it blocks a long time) test_and_clear_bit GLF_DIRTY
It's not dirty (step 7) returns
10. Tests GLF_INVALIDATE_IN_PROGRESS
11. Calls go_inval (rgrp_go_inval)
12. gfs2_rgrp_relse does brelse
13. truncate_inode_pages_range
14. Calls lm_lock UN
In step 14 we've just told dlm to give the glock to another node
when, in fact, process A has not finished the IO and synced all
buffer_heads to disk and make sure their revokes are done.
This patch fixes the problem by changing the GLF_INVALIDATE_IN_PROGRESS
to use test_and_set_bit, and if the bit is already set, process B just
ignores it and trusts that process A will do the do_xmote in the proper
order.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Diffstat (limited to 'fs/gfs2')
| -rw-r--r-- | fs/gfs2/glock.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index faa88bd594e2..b7123de7c180 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -558,7 +558,14 @@ __acquires(&gl->gl_lockref.lock) GLOCK_BUG_ON(gl, gl->gl_state == gl->gl_target); if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) && glops->go_inval) { - set_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags); + /* + * If another process is already doing the invalidate, let that + * finish first. The glock state machine will get back to this + * holder again later. + */ + if (test_and_set_bit(GLF_INVALIDATE_IN_PROGRESS, + &gl->gl_flags)) + return; do_error(gl, 0); /* Fail queued try locks */ } gl->gl_req = target; |