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authorLinus Torvalds <torvalds@linux-foundation.org>2013-05-10 09:02:50 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-05-10 09:02:50 -0700
commitec6671589a07d9b27ff5832138ff435b3a3c9b09 (patch)
tree4866cfd09e45a492b5b96380818fb5d1e3a4fac0 /include
parentf755407dd19072b7d20719bc5454caed9ab41cc1 (diff)
parent2f14f4b51ed34fe2b704af8df178f5cd8c81f65e (diff)
Merge tag 'dm-3.10-changes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm
Pull device-mapper updates from Alasdair Kergon: "Allow devices that hold metadata for the device-mapper thin provisioning target to be extended easily; allow WRITE SAME on multipath devices; an assortment of little fixes and clean-ups." * tag 'dm-3.10-changes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm: (21 commits) dm cache: set config value dm cache: move config fns dm thin: generate event when metadata threshold passed dm persistent metadata: add space map threshold callback dm persistent data: add threshold callback to space map dm thin: detect metadata device resizing dm persistent data: support space map resizing dm thin: open dev read only when possible dm thin: refactor data dev resize dm cache: replace memcpy with struct assignment dm cache: fix typos in comments dm cache policy: fix description of lookup fn dm: document iterate_devices dm persistent data: fix error message typos dm cache: tune migration throttling dm mpath: enable WRITE SAME support dm table: fix write same support dm bufio: avoid a possible __vmalloc deadlock dm snapshot: fix error return code in snapshot_ctr dm cache: fix error return code in cache_create ...
Diffstat (limited to 'include')
-rw-r--r--include/linux/device-mapper.h15
1 files changed, 15 insertions, 0 deletions
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 1e483fa7afb4..3cd32478f2fd 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -79,11 +79,26 @@ typedef int (*dm_ioctl_fn) (struct dm_target *ti, unsigned int cmd,
typedef int (*dm_merge_fn) (struct dm_target *ti, struct bvec_merge_data *bvm,
struct bio_vec *biovec, int max_size);
+/*
+ * These iteration functions are typically used to check (and combine)
+ * properties of underlying devices.
+ * E.g. Does at least one underlying device support flush?
+ * Does any underlying device not support WRITE_SAME?
+ *
+ * The callout function is called once for each contiguous section of
+ * an underlying device. State can be maintained in *data.
+ * Return non-zero to stop iterating through any further devices.
+ */
typedef int (*iterate_devices_callout_fn) (struct dm_target *ti,
struct dm_dev *dev,
sector_t start, sector_t len,
void *data);
+/*
+ * This function must iterate through each section of device used by the
+ * target until it encounters a non-zero return code, which it then returns.
+ * Returns zero if no callout returned non-zero.
+ */
typedef int (*dm_iterate_devices_fn) (struct dm_target *ti,
iterate_devices_callout_fn fn,
void *data);