From 9a4bf31d05a801e2358d96f69b39fb8ce2c69dd8 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Thu, 10 Dec 2015 10:41:58 -0500 Subject: [PATCH] nfs: add new tracepoint for pnfs_update_layout 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 Signed-off-by: Trond Myklebust --- fs/nfs/nfs4trace.h | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++ fs/nfs/pnfs.c | 38 +++++++++++++++++++++++++++++------ include/linux/nfs4.h | 14 +++++++++++++ 3 files changed, 102 insertions(+), 6 deletions(-) diff --git a/fs/nfs/nfs4trace.h b/fs/nfs/nfs4trace.h index 8704372..238925c 100644 --- a/fs/nfs/nfs4trace.h +++ b/fs/nfs/nfs4trace.h @@ -1442,6 +1442,62 @@ DEFINE_NFS4_INODE_STATEID_EVENT(nfs4_layoutcommit); DEFINE_NFS4_INODE_STATEID_EVENT(nfs4_layoutreturn); DEFINE_NFS4_INODE_EVENT(nfs4_layoutreturn_on_close); +#define show_pnfs_update_layout_reason(reason) \ + __print_symbolic(reason, \ + { PNFS_UPDATE_LAYOUT_UNKNOWN, "unknown" }, \ + { PNFS_UPDATE_LAYOUT_NO_PNFS, "no pnfs" }, \ + { PNFS_UPDATE_LAYOUT_RD_ZEROLEN, "read+zerolen" }, \ + { PNFS_UPDATE_LAYOUT_MDSTHRESH, "mdsthresh" }, \ + { PNFS_UPDATE_LAYOUT_NOMEM, "nomem" }, \ + { PNFS_UPDATE_LAYOUT_BULK_RECALL, "bulk recall" }, \ + { PNFS_UPDATE_LAYOUT_IO_TEST_FAIL, "io test fail" }, \ + { PNFS_UPDATE_LAYOUT_FOUND_CACHED, "found cached" }, \ + { PNFS_UPDATE_LAYOUT_RETURN, "layoutreturn" }, \ + { PNFS_UPDATE_LAYOUT_BLOCKED, "layouts blocked" }, \ + { PNFS_UPDATE_LAYOUT_SEND_LAYOUTGET, "sent layoutget" }) + +TRACE_EVENT(pnfs_update_layout, + TP_PROTO(struct inode *inode, + loff_t pos, + u64 count, + enum pnfs_iomode iomode, + struct pnfs_layout_segment *lseg, + enum pnfs_update_layout_reason reason + ), + TP_ARGS(inode, pos, count, iomode, lseg, reason), + TP_STRUCT__entry( + __field(dev_t, dev) + __field(u64, fileid) + __field(u32, fhandle) + __field(loff_t, pos) + __field(u64, count) + __field(enum pnfs_iomode, iomode) + __field(struct pnfs_layout_segment *, lseg) + __field(enum pnfs_update_layout_reason, reason) + ), + TP_fast_assign( + __entry->dev = inode->i_sb->s_dev; + __entry->fileid = NFS_FILEID(inode); + __entry->fhandle = nfs_fhandle_hash(NFS_FH(inode)); + __entry->pos = pos; + __entry->count = count; + __entry->iomode = iomode; + __entry->lseg = lseg; + __entry->reason = reason; + ), + TP_printk( + "fileid=%02x:%02x:%llu fhandle=0x%08x " + "iomode=%s pos=%llu count=%llu lseg=%p (%s)", + MAJOR(__entry->dev), MINOR(__entry->dev), + (unsigned long long)__entry->fileid, + __entry->fhandle, + show_pnfs_iomode(__entry->iomode), + (unsigned long long)__entry->pos, + (unsigned long long)__entry->count, __entry->lseg, + show_pnfs_update_layout_reason(__entry->reason) + ) +); + #endif /* CONFIG_NFS_V4_1 */ #endif /* _TRACE_NFS4_H */ diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c index bec0384..1489065 100644 --- a/fs/nfs/pnfs.c +++ b/fs/nfs/pnfs.c @@ -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); diff --git a/include/linux/nfs4.h b/include/linux/nfs4.h index e7e7853..0e30f2c 100644 --- a/include/linux/nfs4.h +++ b/include/linux/nfs4.h @@ -592,4 +592,18 @@ enum data_content4 { NFS4_CONTENT_HOLE = 1, }; +enum pnfs_update_layout_reason { + PNFS_UPDATE_LAYOUT_UNKNOWN = 0, + PNFS_UPDATE_LAYOUT_NO_PNFS, + PNFS_UPDATE_LAYOUT_RD_ZEROLEN, + PNFS_UPDATE_LAYOUT_MDSTHRESH, + PNFS_UPDATE_LAYOUT_NOMEM, + PNFS_UPDATE_LAYOUT_BULK_RECALL, + PNFS_UPDATE_LAYOUT_IO_TEST_FAIL, + PNFS_UPDATE_LAYOUT_FOUND_CACHED, + PNFS_UPDATE_LAYOUT_RETURN, + PNFS_UPDATE_LAYOUT_BLOCKED, + PNFS_UPDATE_LAYOUT_SEND_LAYOUTGET, +}; + #endif -- 2.7.4