GFS2: Improve block reservation tracing

This patch improves the tracing of block reservations by
removing some corner cases and also providing more useful
detail in the traces.

A new field is added to the reservation structure to contain
the inode number. This is used since in certain contexts it is
not possible to access the inode itself to obtain this information.
As a result we can then display the inode number for all tracepoints
and also in case we dump the resource group.

The "del" tracepoint operation has been removed. This could be called
with the reservation rgrp set to NULL. That resulted in not printing
the device number, and thus making the information largely useless
anyway. Also, the conditional on the rgrp being NULL can then be
removed from the tracepoint. After this change, all the block
reservation tracepoint calls will be called with the rgrp information.

The existing ins,clm and tdel calls to the block reservation tracepoint
are sufficient to track the entire life of the block reservation.

In gfs2_block_alloc() the error detection is updated to print out
the inode number of the problematic inode. This can then be compared
against the information in the glock dump,tracepoints, etc.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 2 insertions, 4 deletions

diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index 99d7c64b5091..6aaa07c7c731 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -268,13 +268,11 @@ struct gfs2_blkreserv {
 	/* components used during write (step 1): */
 	atomic_t rs_sizehint;         /* hint of the write size */
 
-	/* components used during get_local_rgrp (step 3): */
-	struct gfs2_rbm rs_rbm;
 	struct gfs2_holder rs_rgd_gh; /* Filled in by get_local_rgrp */
 	struct rb_node rs_node;       /* link to other block reservations */
-
-	/* components used during block searches and assignments (step 4): */
+	struct gfs2_rbm rs_rbm;       /* Start of reservation */
 	u32 rs_free;                  /* how many blocks are still free */
+	u64 rs_inum;                  /* Inode number for reservation */
 
 	/* ancillary quota stuff */
 	struct gfs2_quota_data *rs_qa_qd[2 * MAXQUOTAS];