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nfs: add new tracepoint for pnfs_update_layout

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pnfs_update_layout is really the "nexus" of layout handling. If it
returns NULL then we end up going through the MDS. This patch adds
some tracepoints to that function that allow us to determine the
cause when we end up going through the MDS unexpectedly.

Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This commit is contained in:
Jeff Layton
2015-12-10 10:41:58 -05:00
committed by Trond Myklebust
parent 9759b0fb1d
commit 9a4bf31d05
3 changed files with 102 additions and 6 deletions
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38
fs/nfs/pnfs.c
View File

@@ -1520,14 +1520,23 @@ pnfs_update_layout(struct inode *ino,
struct pnfs_layout_segment *lseg = NULL;
bool first;
if (!pnfs_enabled_sb(NFS_SERVER(ino)))
if (!pnfs_enabled_sb(NFS_SERVER(ino))) {
trace_pnfs_update_layout(ino, pos, count, iomode, lseg,
PNFS_UPDATE_LAYOUT_NO_PNFS);
goto out;
}
if (iomode == IOMODE_READ && i_size_read(ino) == 0)
if (iomode == IOMODE_READ && i_size_read(ino) == 0) {
trace_pnfs_update_layout(ino, pos, count, iomode, lseg,
PNFS_UPDATE_LAYOUT_RD_ZEROLEN);
goto out;
}
if (pnfs_within_mdsthreshold(ctx, ino, iomode))
if (pnfs_within_mdsthreshold(ctx, ino, iomode)) {
trace_pnfs_update_layout(ino, pos, count, iomode, lseg,
PNFS_UPDATE_LAYOUT_MDSTHRESH);
goto out;
}
lookup_again:
first = false;
@@ -1535,19 +1544,26 @@ lookup_again:
lo = pnfs_find_alloc_layout(ino, ctx, gfp_flags);
if (lo == NULL) {
spin_unlock(&ino->i_lock);
trace_pnfs_update_layout(ino, pos, count, iomode, lseg,
PNFS_UPDATE_LAYOUT_NOMEM);
goto out;
}
/* Do we even need to bother with this? */
if (test_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags)) {
trace_pnfs_update_layout(ino, pos, count, iomode, lseg,
PNFS_UPDATE_LAYOUT_BULK_RECALL);
dprintk("%s matches recall, use MDS\n", __func__);
goto out_unlock;
}
/* if LAYOUTGET already failed once we don't try again */
if (pnfs_layout_io_test_failed(lo, iomode) &&
!pnfs_should_retry_layoutget(lo))
!pnfs_should_retry_layoutget(lo)) {
trace_pnfs_update_layout(ino, pos, count, iomode, lseg,
PNFS_UPDATE_LAYOUT_IO_TEST_FAIL);
goto out_unlock;
}
first = list_empty(&lo->plh_segs);
if (first) {
@@ -1567,8 +1583,11 @@ lookup_again:
* already exists
*/
lseg = pnfs_find_lseg(lo, &arg);
if (lseg)
if (lseg) {
trace_pnfs_update_layout(ino, pos, count, iomode, lseg,
PNFS_UPDATE_LAYOUT_FOUND_CACHED);
goto out_unlock;
}
}
/*
@@ -1585,11 +1604,16 @@ lookup_again:
dprintk("%s retrying\n", __func__);
goto lookup_again;
}
trace_pnfs_update_layout(ino, pos, count, iomode, lseg,
PNFS_UPDATE_LAYOUT_RETURN);
goto out_put_layout_hdr;
}
if (pnfs_layoutgets_blocked(lo))
if (pnfs_layoutgets_blocked(lo)) {
trace_pnfs_update_layout(ino, pos, count, iomode, lseg,
PNFS_UPDATE_LAYOUT_BLOCKED);
goto out_unlock;
}
atomic_inc(&lo->plh_outstanding);
spin_unlock(&ino->i_lock);
@@ -1614,6 +1638,8 @@ lookup_again:
lseg = send_layoutget(lo, ctx, &arg, gfp_flags);
pnfs_clear_retry_layoutget(lo);
atomic_dec(&lo->plh_outstanding);
trace_pnfs_update_layout(ino, pos, count, iomode, lseg,
PNFS_UPDATE_LAYOUT_SEND_LAYOUTGET);
out_put_layout_hdr:
if (first)
pnfs_clear_first_layoutget(lo);