Introduce read/write kstats per dataset

The following patch introduces a few statistics on reads and writes
grouped by dataset. These statistics are implemented as kstats
(backed by aggregate sums for performance) and can be retrieved by
using the dataset objset ID number. The motivation for this change is
to provide some preliminary analytics on dataset usage/performance.

Reviewed-by: Richard Elling <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed by: Matthew Ahrens <[email protected]>
Signed-off-by: Serapheim Dimitropoulos <[email protected]>
Closes #7705 

1 files changed, 51 insertions, 54 deletions

diff --git a/module/zfs/zfs_vnops.c b/module/zfs/zfs_vnops.c
index 35bbd884b..4e163e2e3 100644
--- a/module/zfs/zfs_vnops.c
+++ b/module/zfs/zfs_vnops.c
@@ -21,7 +21,7 @@
 
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2012, 2015 by Delphix. All rights reserved.
+ * Copyright (c) 2012, 2018 by Delphix. All rights reserved.
  * Copyright (c) 2015 by Chunwei Chen. All rights reserved.
  * Copyright 2017 Nexenta Systems, Inc.
  */
@@ -438,15 +438,10 @@ unsigned long zfs_delete_blocks = DMU_MAX_DELETEBLKCNT;
 int
 zfs_read(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
 {
-	znode_t		*zp = ITOZ(ip);
-	zfsvfs_t	*zfsvfs = ITOZSB(ip);
-	ssize_t		n, nbytes;
-	int		error = 0;
-	rl_t		*rl;
-#ifdef HAVE_UIO_ZEROCOPY
-	xuio_t		*xuio = NULL;
-#endif /* HAVE_UIO_ZEROCOPY */
+	int error = 0;
 
+	znode_t *zp = ITOZ(ip);
+	zfsvfs_t *zfsvfs = ITOZSB(ip);
 	ZFS_ENTER(zfsvfs);
 	ZFS_VERIFY_ZP(zp);
 
@@ -482,8 +477,8 @@ zfs_read(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
 	/*
 	 * Lock the range against changes.
 	 */
-	rl = zfs_range_lock(&zp->z_range_lock, uio->uio_loffset, uio->uio_resid,
-	    RL_READER);
+	rl_t *rl = zfs_range_lock(&zp->z_range_lock,
+	    uio->uio_loffset, uio->uio_resid, RL_READER);
 
 	/*
 	 * If we are reading past end-of-file we can skip
@@ -495,9 +490,11 @@ zfs_read(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
 	}
 
 	ASSERT(uio->uio_loffset < zp->z_size);
-	n = MIN(uio->uio_resid, zp->z_size - uio->uio_loffset);
+	ssize_t n = MIN(uio->uio_resid, zp->z_size - uio->uio_loffset);
+	ssize_t start_resid = n;
 
 #ifdef HAVE_UIO_ZEROCOPY
+	xuio_t *xuio = NULL;
 	if ((uio->uio_extflg == UIO_XUIO) &&
 	    (((xuio_t *)uio)->xu_type == UIOTYPE_ZEROCOPY)) {
 		int nblk;
@@ -529,7 +526,7 @@ zfs_read(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
 #endif /* HAVE_UIO_ZEROCOPY */
 
 	while (n > 0) {
-		nbytes = MIN(n, zfs_read_chunk_size -
+		ssize_t nbytes = MIN(n, zfs_read_chunk_size -
 		    P2PHASE(uio->uio_loffset, zfs_read_chunk_size));
 
 		if (zp->z_is_mapped && !(ioflag & O_DIRECT)) {
@@ -548,6 +545,10 @@ zfs_read(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
 
 		n -= nbytes;
 	}
+
+	int64_t nread = start_resid - n;
+	dataset_kstats_update_read_kstats(&zfsvfs->z_kstat, nread);
+	task_io_account_read(nread);
 out:
 	zfs_range_unlock(rl);
 
@@ -578,46 +579,28 @@ out:
 int
 zfs_write(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
 {
-	znode_t		*zp = ITOZ(ip);
-	rlim64_t	limit = uio->uio_limit;
-	ssize_t		start_resid = uio->uio_resid;
-	ssize_t		tx_bytes;
-	uint64_t	end_size;
-	dmu_tx_t	*tx;
-	zfsvfs_t	*zfsvfs = ZTOZSB(zp);
-	zilog_t		*zilog;
-	offset_t	woff;
-	ssize_t		n, nbytes;
-	rl_t		*rl;
-	int		max_blksz = zfsvfs->z_max_blksz;
-	int		error = 0;
-	arc_buf_t	*abuf;
-	const iovec_t	*aiov = NULL;
-	xuio_t		*xuio = NULL;
-	int		write_eof;
-	int		count = 0;
-	sa_bulk_attr_t	bulk[4];
-	uint64_t	mtime[2], ctime[2];
-	uint32_t	uid;
-#ifdef HAVE_UIO_ZEROCOPY
-	int		i_iov = 0;
-	const iovec_t	*iovp = uio->uio_iov;
-	ASSERTV(int	iovcnt = uio->uio_iovcnt);
-#endif
+	int error = 0;
+	ssize_t start_resid = uio->uio_resid;
 
 	/*
 	 * Fasttrack empty write
 	 */
-	n = start_resid;
+	ssize_t n = start_resid;
 	if (n == 0)
 		return (0);
 
+	rlim64_t limit = uio->uio_limit;
 	if (limit == RLIM64_INFINITY || limit > MAXOFFSET_T)
 		limit = MAXOFFSET_T;
 
+	znode_t *zp = ITOZ(ip);
+	zfsvfs_t *zfsvfs = ZTOZSB(zp);
 	ZFS_ENTER(zfsvfs);
 	ZFS_VERIFY_ZP(zp);
 
+	sa_bulk_attr_t bulk[4];
+	int count = 0;
+	uint64_t mtime[2], ctime[2];
 	SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_MTIME(zfsvfs), NULL, &mtime, 16);
 	SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CTIME(zfsvfs), NULL, &ctime, 16);
 	SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_SIZE(zfsvfs), NULL,
@@ -644,17 +627,18 @@ zfs_write(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
 		return (SET_ERROR(EPERM));
 	}
 
-	zilog = zfsvfs->z_log;
-
 	/*
 	 * Validate file offset
 	 */
-	woff = ioflag & FAPPEND ? zp->z_size : uio->uio_loffset;
+	offset_t woff = ioflag & FAPPEND ? zp->z_size : uio->uio_loffset;
 	if (woff < 0) {
 		ZFS_EXIT(zfsvfs);
 		return (SET_ERROR(EINVAL));
 	}
 
+	int max_blksz = zfsvfs->z_max_blksz;
+	xuio_t *xuio = NULL;
+
 	/*
 	 * Pre-fault the pages to ensure slow (eg NFS) pages
 	 * don't hold up txg.
@@ -668,6 +652,8 @@ zfs_write(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
 #endif
 		uio_prefaultpages(MIN(n, max_blksz), uio);
 
+	rl_t	 *rl;
+
 	/*
 	 * If in append mode, set the io offset pointer to eof.
 	 */
@@ -706,9 +692,16 @@ zfs_write(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
 		n = limit - woff;
 
 	/* Will this write extend the file length? */
-	write_eof = (woff + n > zp->z_size);
+	int write_eof = (woff + n > zp->z_size);
+
+	uint64_t end_size = MAX(zp->z_size, woff + n);
+	zilog_t *zilog = zfsvfs->z_log;
+#ifdef HAVE_UIO_ZEROCOPY
+	int		i_iov = 0;
+	const iovec_t	*iovp = uio->uio_iov;
+	ASSERTV(int	iovcnt = uio->uio_iovcnt);
+#endif
 
-	end_size = MAX(zp->z_size, woff + n);
 
 	/*
 	 * Write the file in reasonable size chunks.  Each chunk is written
@@ -716,8 +709,8 @@ zfs_write(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
 	 * and allows us to do more fine-grained space accounting.
 	 */
 	while (n > 0) {
-		abuf = NULL;
 		woff = uio->uio_loffset;
+
 		if (zfs_id_overblockquota(zfsvfs, DMU_USERUSED_OBJECT,
 		    KUID_TO_SUID(ip->i_uid)) ||
 		    zfs_id_overblockquota(zfsvfs, DMU_GROUPUSED_OBJECT,
@@ -725,13 +718,13 @@ zfs_write(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
 		    (zp->z_projid != ZFS_DEFAULT_PROJID &&
 		    zfs_id_overblockquota(zfsvfs, DMU_PROJECTUSED_OBJECT,
 		    zp->z_projid))) {
-			if (abuf != NULL)
-				dmu_return_arcbuf(abuf);
 			error = SET_ERROR(EDQUOT);
 			break;
 		}
 
-		if (xuio && abuf == NULL) {
+		arc_buf_t *abuf = NULL;
+		const iovec_t *aiov = NULL;
+		if (xuio) {
 #ifdef HAVE_UIO_ZEROCOPY
 			ASSERT(i_iov < iovcnt);
 			ASSERT3U(uio->uio_segflg, !=, UIO_BVEC);
@@ -743,8 +736,7 @@ zfs_write(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
 			    aiov->iov_len == arc_buf_size(abuf)));
 			i_iov++;
 #endif
-		} else if (abuf == NULL && n >= max_blksz &&
-		    woff >= zp->z_size &&
+		} else if (n >= max_blksz && woff >= zp->z_size &&
 		    P2PHASE(woff, max_blksz) == 0 &&
 		    zp->z_blksz == max_blksz) {
 			/*
@@ -771,7 +763,7 @@ zfs_write(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
 		/*
 		 * Start a transaction.
 		 */
-		tx = dmu_tx_create(zfsvfs->z_os);
+		dmu_tx_t *tx = dmu_tx_create(zfsvfs->z_os);
 		dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_FALSE);
 		dmu_tx_hold_write(tx, zp->z_id, woff, MIN(n, max_blksz));
 		zfs_sa_upgrade_txholds(tx, zp);
@@ -812,8 +804,9 @@ zfs_write(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
 		 * XXX - should we really limit each write to z_max_blksz?
 		 * Perhaps we should use SPA_MAXBLOCKSIZE chunks?
 		 */
-		nbytes = MIN(n, max_blksz - P2PHASE(woff, max_blksz));
+		ssize_t nbytes = MIN(n, max_blksz - P2PHASE(woff, max_blksz));
 
+		ssize_t tx_bytes;
 		if (abuf == NULL) {
 			tx_bytes = uio->uio_resid;
 			error = dmu_write_uio_dbuf(sa_get_db(zp->z_sa_hdl),
@@ -873,7 +866,7 @@ zfs_write(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
 		 * user 0 is not an ephemeral uid.
 		 */
 		mutex_enter(&zp->z_acl_lock);
-		uid = KUID_TO_SUID(ip->i_uid);
+		uint32_t uid = KUID_TO_SUID(ip->i_uid);
 		if ((zp->z_mode & (S_IXUSR | (S_IXUSR >> 3) |
 		    (S_IXUSR >> 6))) != 0 &&
 		    (zp->z_mode & (S_ISUID | S_ISGID)) != 0 &&
@@ -937,6 +930,10 @@ zfs_write(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
 	    zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS)
 		zil_commit(zilog, zp->z_id);
 
+	int64_t nwritten = start_resid - uio->uio_resid;
+	dataset_kstats_update_write_kstats(&zfsvfs->z_kstat, nwritten);
+	task_io_account_write(nwritten);
+
 	ZFS_EXIT(zfsvfs);
 	return (0);
 }