linux/Documentation/device-mapper, branch v3.16

dm thin: add 'no_space_timeout' dm-thin-pool module param

2014-05-20T18:30:36Z

Commit 85ad643b ("dm thin: add timeout to stop out-of-data-space mode holding IO forever") introduced a fixed 60 second timeout. Users may want to either disable or modify this timeout. Allow the out-of-data-space timeout to be configured using the 'no_space_timeout' dm-thin-pool module param. Setting it to 0 will disable the timeout, resulting in IO being queued until more data space is added to the thin-pool. Signed-off-by: Mike Snitzer Cc: stable@vger.kernel.org # 3.14+

dm: add era target

2014-03-27T20:56:23Z

dm-era is a target that behaves similar to the linear target. In addition it keeps track of which blocks were written within a user defined period of time called an 'era'. Each era target instance maintains the current era as a monotonically increasing 32-bit counter. Use cases include tracking changed blocks for backup software, and partially invalidating the contents of a cache to restore cache coherency after rolling back a vendor snapshot. dm-era is primarily expected to be paired with the dm-cache target. Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer

dm thin: fix Documentation for held metadata root feature

2014-03-06T19:23:35Z

The Documentation for the thin provisioning target's held metadata root feature was incorrect. It is now available and the value for the held metadata root is in block units (not 512b sectors). Signed-off-by: Mike Snitzer

dm thin: ensure user takes action to validate data and metadata consistency

2014-03-05T20:25:35Z

If a thin metadata operation fails the current transaction will abort, whereby causing potential for IO layers up the stack (e.g. filesystems) to have data loss. As such, set THIN_METADATA_NEEDS_CHECK_FLAG in the thin metadata's superblock which: 1) requires the user verify the thin metadata is consistent (e.g. use thin_check, etc) 2) suggests the user verify the thin data is consistent (e.g. use fsck) The only way to clear the superblock's THIN_METADATA_NEEDS_CHECK_FLAG is to run thin_repair. On metadata operation failure: abort current metadata transaction, set pool in read-only mode, and now set the needs_check flag. As part of this change, constraints are introduced or relaxed: * don't allow a pool to transition to write mode if needs_check is set * don't allow data or metadata space to be resized if needs_check is set * if a thin pool's metadata space is exhausted: the kernel will now force the user to take the pool offline for repair before the kernel will allow the metadata space to be extended. Also, update Documentation to include information about when the thin provisioning target commits metadata, how it handles metadata failures and running out of space. Signed-off-by: Mike Snitzer Signed-off-by: Joe Thornber

dm cache: add policy name to status output

2014-01-16T18:44:11Z

The cache's policy may have been established using the "default" alias, which is currently the "mq" policy but the default policy may change in the future. It is useful to know exactly which policy is being used. Add a 'real' member to the dm_cache_policy_type structure and have the "default" dm_cache_policy_type point to the real "mq" dm_cache_policy_type. Update dm_cache_policy_get_name() to check if real is set, if so report the name of the real policy (not the alias). Requested-by: Jonathan Brassow Signed-off-by: Mike Snitzer

dm cache: add block sizes and total cache blocks to status output

2014-01-10T15:24:33Z

Improve cache_status to emit: <#used metadata blocks>/<#total metadata blocks> <#used cache blocks>/<#total cache blocks> ... Adding the block sizes allows for easier calculation of the overall size of both the metadata and cache devices. Adding <#total cache blocks> provides useful context for how much of the cache is used. Unfortunately these additions to the status will require updates to users' scripts that monitor the cache status. But these changes help provide more comprehensive information about the cache device and will simplify tools that are being developed to manage dm-cache devices -- because they won't need to issue 3 operations to cobble together the information that we can easily provide via a single status ioctl. While updating the status documentation in cache.txt spaces were tabify'd. Requested-by: Jonathan Brassow Signed-off-by: Mike Snitzer Acked-by: Joe Thornber

dm cache policy mq: introduce three promotion threshold tunables

2014-01-07T15:14:33Z

Internally the mq policy maintains a promotion threshold variable. If the hit count of a block not in the cache goes above this threshold it gets promoted to the cache. This patch introduces three new tunables that allow you to tweak the promotion threshold by adding a small value. These adjustments depend on the io type: read_promote_adjustment: READ io, default 4 write_promote_adjustment: WRITE io, default 8 discard_promote_adjustment: READ/WRITE io to a discarded block, default 1 If you're trying to quickly warm a new cache device you may wish to reduce these to encourage promotion. Remember to switch them back to their defaults after the cache fills though. Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer

dm thin: add error_if_no_space feature

2014-01-07T15:14:30Z

If the pool runs out of data or metadata space, the pool can either queue or error the IO destined to the data device. The default is to queue the IO until more space is added. An admin may now configure the pool to error IO when no space is available by setting the 'error_if_no_space' feature when loading the thin-pool table. Signed-off-by: Mike Snitzer Acked-by: Joe Thornber

dm cache: update Documentation for invalidate_cblocks's range syntax

2013-12-10T21:35:15Z

The cache target's invalidate_cblocks message allows cache block (cblock) ranges to be expressed with: - The range's value is "one past the end", so the range includes through -1. Signed-off-by: Mike Snitzer Acked-by: Joe Thornber

dm cache: resolve small nits and improve Documentation

2013-11-12T18:11:09Z

Document passthrough mode, cache shrinking, and cache invalidation. Also, use strcasecmp() and hlist_unhashed(). Reported-by: Alasdair G Kergon Signed-off-by: Mike Snitzer