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Add support for DISCARD to ZVOLs.

Browse Source 
DISCARD (REQ_DISCARD, BLKDISCARD) is useful for thin provisioning.
It allows ZVOL clients to discard (unmap, trim) block ranges from
a ZVOL, thus optimizing disk space usage by allowing a ZVOL to
shrink instead of just grow.

We can't use zfs_space() or zfs_freesp() here, since these functions
only work on regular files, not volumes. Fortunately we can use the
low-level function dmu_free_long_range() which does exactly what we
want.

Currently the discard operation is not added to the log. That's not
a big deal since losing discard requests cannot result in data
corruption. It would however result in disk space usage higher than
it should be. Thus adding log support to zvol_discard() is probably
a good idea for a future improvement.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
This commit is contained in:
Etienne Dechamps
2011-09-02 15:23:12 +02:00
committed by Brian Behlendorf
parent cb2d19010d
commit 30930fba21
60 changed files with 273 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files
include/Makefile.in
+1
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@@ -51,6 +51,7 @@ am__aclocal_m4_deps = \
$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
$(top_srcdir)/config/kernel-blk-end-request.m4 \
$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \
include/linux/Makefile.in
+1
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@@ -51,6 +51,7 @@ am__aclocal_m4_deps = \
$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
$(top_srcdir)/config/kernel-blk-end-request.m4 \
$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \
include/linux/blkdev_compat.h
+8
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@@ -424,6 +424,14 @@ bio_set_flags_failfast(struct block_device *bdev, int *flags)
# define VDEV_REQ_FUA REQ_HARDBARRIER
#endif
/*
* 2.6.32 API change
* Use the normal I/O patch for discards.
*/
#ifdef REQ_DISCARD
# define VDEV_REQ_DISCARD REQ_DISCARD
#endif
/*
* Default Linux IO Scheduler,
* Setting the scheduler to noop will allow the Linux IO scheduler to
include/sys/Makefile.in
+1
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@@ -51,6 +51,7 @@ am__aclocal_m4_deps = \
$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
$(top_srcdir)/config/kernel-blk-end-request.m4 \
$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \
include/sys/fm/Makefile.in
+1
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@@ -51,6 +51,7 @@ am__aclocal_m4_deps = \
$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
$(top_srcdir)/config/kernel-blk-end-request.m4 \
$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \
include/sys/fm/fs/Makefile.in
+1
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@@ -51,6 +51,7 @@ am__aclocal_m4_deps = \
$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
$(top_srcdir)/config/kernel-blk-end-request.m4 \
$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \
include/sys/fs/Makefile.in
+1
View File
@@ -51,6 +51,7 @@ am__aclocal_m4_deps = \
$(top_srcdir)/config/kernel-bio-rw-syncio.m4 \
$(top_srcdir)/config/kernel-blk-end-request.m4 \
$(top_srcdir)/config/kernel-blk-fetch-request.m4 \
$(top_srcdir)/config/kernel-blk-queue-discard.m4 \
$(top_srcdir)/config/kernel-blk-queue-flush.m4 \
$(top_srcdir)/config/kernel-blk-queue-io-opt.m4 \
$(top_srcdir)/config/kernel-blk-queue-max-hw-sectors.m4 \