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MFV r323917: 8648 Fix range locking in ZIL commit codepath

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illumos/illumos-gate@42b1411172
42b1411172

https://www.illumos.org/issues/8648
  I'm opening this bug to track integration of the following ZFS on Linux
  commit into illumos:

  commit f763c3d1df569a8d6b60bcb5e95cf07aa7a189e6
  Author: LOLi <loli10K@users.noreply.github.com>
  Date:   Mon Aug 21 17:59:48 2017 +0200

      Fix range locking in ZIL commit codepath

      Since OpenZFS 7578 (1b7c1e5) if we have a ZVOL with logbias=throughput
      we will force WR_INDIRECT itxs in zvol_log_write() setting itx->itx_lr
      offset and length to the offset and length of the BIO from
      zvol_write()->zvol_log_write(): these offset and length are later used
      to take a range lock in zillog->zl_get_data function: zvol_get_data().

      Now suppose we have a ZVOL with blocksize=8K and push 4K writes to
      offset 0: we will only be range-locking 0-4096. This means the
      ASSERTion we make in dbuf_unoverride() is no longer valid because now
      dmu_sync() is called from zilog's get_data functions holding a partial
      lock on the dbuf.

      Fix this by taking a range lock on the whole block in zvol_get_data().

      Reviewed-by: Chunwei Chen <tuxoko@gmail.com>
      Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
      Signed-off-by: loli10K <ezomori.nozomu@gmail.com>

Reviewed by: Igor Kozhukhov <igor@dilos.org>
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Reviewed by: Andriy Gapon <avg@FreeBSD.org>
Reviewed by: Alexander Motin <mav@FreeBSD.org>
Approved by: Robert Mustacchi <rm@joyent.com>
Author: LOLi <loli10K@users.noreply.github.com>

MFC after:	10 days
This commit is contained in:
avg 2017-09-22 08:27:27 +00:00
parent 118c173868
commit 7392d39323
2 changed files with 13 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
View File

@ -1343,7 +1343,7 @@ zfs_get_data(void *arg, lr_write_t *lr, char *buf, zio_t *zio)
} else { /* indirect write */
/*
* Have to lock the whole block to ensure when it's
* written out and it's checksum is being calculated
* written out and its checksum is being calculated
* that no one can change the data. We need to re-check
* blocksize after we get the lock in case it's changed!
*/

15
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zvol.c
View File

@ -1349,7 +1349,6 @@ zvol_get_data(void *arg, lr_write_t *lr, char *buf, zio_t *zio)
zgd = kmem_zalloc(sizeof (zgd_t), KM_SLEEP);
zgd->zgd_zilog = zv->zv_zilog;
zgd->zgd_rl = zfs_range_lock(&zv->zv_znode, offset, size, RL_READER);
/*
* Write records come in two flavors: immediate and indirect.
@ -1358,12 +1357,22 @@ zvol_get_data(void *arg, lr_write_t *lr, char *buf, zio_t *zio)
* sync the data and get a pointer to it (indirect) so that
* we don't have to write the data twice.
*/
if (buf != NULL) { /* immediate write */
if (buf != NULL) { /* immediate write */
zgd->zgd_rl = zfs_range_lock(&zv->zv_znode, offset, size,
RL_READER);
error = dmu_read(os, object, offset, size, buf,
DMU_READ_NO_PREFETCH);
} else {
} else { /* indirect write */
/*
* Have to lock the whole block to ensure when it's written out
* and its checksum is being calculated that no one can change
* the data. Contrarily to zfs_get_data we need not re-check
* blocksize after we get the lock because it cannot be changed.
*/
size = zv->zv_volblocksize;
offset = P2ALIGN(offset, size);
zgd->zgd_rl = zfs_range_lock(&zv->zv_znode, offset, size,
RL_READER);
error = dmu_buf_hold(os, object, offset, zgd, &db,
DMU_READ_NO_PREFETCH);
if (error == 0) {