diff options
| author | Bob Peterson <rpeterso@redhat.com> | 2018-04-18 13:58:19 -0700 |
|---|---|---|
| committer | Andreas Gruenbacher <agruenba@redhat.com> | 2021-02-17 19:30:28 +0100 |
| commit | 06e908cd9ead1f215cc30132aac5ce132a352fbe (patch) | |
| tree | d29700f1ed155b18a0b3bd0af553f48fbc1a35af /fs/gfs2 | |
| parent | 9e514605c77451745ea9fca5a26fc3153893686a (diff) | |
gfs2: Allow node-wide exclusive glock sharing
Introduce a new LM_FLAG_NODE_SCOPE glock holder flag: when taking a
glock in LM_ST_EXCLUSIVE (EX) mode and with the LM_FLAG_NODE_SCOPE flag
set, the exclusive lock is shared among all local processes who are
holding the glock in EX mode and have the LM_FLAG_NODE_SCOPE flag set.
From the point of view of other nodes, the lock is still held
exclusively.
A future patch will start using this flag to improve performance with
rgrp sharing.
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 | 22 | ||||
| -rw-r--r-- | fs/gfs2/glock.h | 6 |
2 files changed, 25 insertions, 3 deletions
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index d87a5bc3607b..9567520d79f7 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -313,9 +313,23 @@ void gfs2_glock_put(struct gfs2_glock *gl) static inline int may_grant(const struct gfs2_glock *gl, const struct gfs2_holder *gh) { const struct gfs2_holder *gh_head = list_first_entry(&gl->gl_holders, const struct gfs2_holder, gh_list); - if ((gh->gh_state == LM_ST_EXCLUSIVE || - gh_head->gh_state == LM_ST_EXCLUSIVE) && gh != gh_head) - return 0; + + if (gh != gh_head) { + /** + * Here we make a special exception to grant holders who agree + * to share the EX lock with other holders who also have the + * bit set. If the original holder has the LM_FLAG_NODE_SCOPE bit + * is set, we grant more holders with the bit set. + */ + if (gh_head->gh_state == LM_ST_EXCLUSIVE && + (gh_head->gh_flags & LM_FLAG_NODE_SCOPE) && + gh->gh_state == LM_ST_EXCLUSIVE && + (gh->gh_flags & LM_FLAG_NODE_SCOPE)) + return 1; + if ((gh->gh_state == LM_ST_EXCLUSIVE || + gh_head->gh_state == LM_ST_EXCLUSIVE)) + return 0; + } if (gl->gl_state == gh->gh_state) return 1; if (gh->gh_flags & GL_EXACT) @@ -2030,6 +2044,8 @@ static const char *hflags2str(char *buf, u16 flags, unsigned long iflags) *p++ = 'A'; if (flags & LM_FLAG_PRIORITY) *p++ = 'p'; + if (flags & LM_FLAG_NODE_SCOPE) + *p++ = 'n'; if (flags & GL_ASYNC) *p++ = 'a'; if (flags & GL_EXACT) diff --git a/fs/gfs2/glock.h b/fs/gfs2/glock.h index 53813364517b..31a8f2f649b5 100644 --- a/fs/gfs2/glock.h +++ b/fs/gfs2/glock.h @@ -75,6 +75,11 @@ enum { * request and directly join the other shared lock. A shared lock request * without the priority flag might be forced to wait until the deferred * requested had acquired and released the lock. + * + * LM_FLAG_NODE_SCOPE + * This holder agrees to share the lock within this node. In other words, + * the glock is held in EX mode according to DLM, but local holders on the + * same node can share it. */ #define LM_FLAG_TRY 0x0001 @@ -82,6 +87,7 @@ enum { #define LM_FLAG_NOEXP 0x0004 #define LM_FLAG_ANY 0x0008 #define LM_FLAG_PRIORITY 0x0010 +#define LM_FLAG_NODE_SCOPE 0x0020 #define GL_ASYNC 0x0040 #define GL_EXACT 0x0080 #define GL_SKIP 0x0100 |