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authorEtienne Dechamps <[email protected]>2011-09-02 15:23:12 +0200
committerBrian Behlendorf <[email protected]>2012-02-09 16:19:38 -0800
commit30930fba219642cb1dadf1c8ef60ff799e3dc424 (patch)
tree093f2c5c254768e859f8307d77d393e9668b5e1f /include/linux
parentcb2d19010d8fbcf6c22585cd8763fad3ba7db724 (diff)
Add support for DISCARD to ZVOLs.
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 <[email protected]>
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/Makefile.in1
-rw-r--r--include/linux/blkdev_compat.h8
2 files changed, 9 insertions, 0 deletions
diff --git a/include/linux/Makefile.in b/include/linux/Makefile.in
index d18e5dd9c..9c69b6257 100644
--- a/include/linux/Makefile.in
+++ b/include/linux/Makefile.in
@@ -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 \
diff --git a/include/linux/blkdev_compat.h b/include/linux/blkdev_compat.h
index 56a1bafe9..bd1b2bf54 100644
--- a/include/linux/blkdev_compat.h
+++ b/include/linux/blkdev_compat.h
@@ -425,6 +425,14 @@ bio_set_flags_failfast(struct block_device *bdev, int *flags)
#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
* still perform front and back merging, while leaving the request