kernel/git/stable/linux.git/drivers/md/dm-thin.c, branch linux-3.6.y

dm thin: fix discard support for data devices

2012-09-26T22:45:47+00:00

The discard limits that get established for a thin-pool or thin device may be incompatible with the pool's data device. Avoid this by checking the discard limits of the pool's data device. If an incompatibility is found then the pool's 'discard passdown' feature is disabled. Change thin_io_hints to ensure that a thin device always uses the same queue limits as its pool device. Introduce requested_pf to track whether or not the table line originally contained the no_discard_passdown flag and use this directly for table output. We prepare the correct setting for discard_passdown directly in bind_control_target (called from pool_io_hints) and store it in adjusted_pf rather than waiting until we have access to pool->pf in pool_preresume. Signed-off-by: Mike Snitzer Signed-off-by: Joe Thornber Signed-off-by: Alasdair G Kergon

dm thin: tidy discard support

2012-09-26T22:45:46+00:00

A little thin discard code refactoring to make the next patch (dm thin: fix discard support for data devices) more readable. Pull out a couple of functions (and uses bools instead of unsigned for features). No functional changes. Signed-off-by: Mike Snitzer Signed-off-by: Joe Thornber Signed-off-by: Alasdair G Kergon

dm thin: do not set discard_zeroes_data

2012-09-26T22:45:39+00:00

The dm thin pool target claims to support the zeroing of discarded data areas. This turns out to be incorrect when processing discards that do not exactly cover a complete number of blocks, so the target must always set discard_zeroes_data_unsupported. The thin pool target will zero blocks when they are allocated if the skip_block_zeroing feature is not specified. The block layer may send a discard that only partly covers a block. If a thin pool block is partially discarded then there is no guarantee that the discarded data will get zeroed before it is accessed again. Due to this, thin devices cannot claim discards will always zero data. Signed-off-by: Mike Snitzer Signed-off-by: Joe Thornber Cc: stable@vger.kernel.org # 3.4+ Signed-off-by: Alasdair G Kergon

dm thin: commit before gathering status

2012-07-27T14:08:16+00:00

Commit outstanding metadata before returning the status for a dm thin pool so that the numbers reported are as up-to-date as possible. The commit is not performed if the device is suspended or if the DM_NOFLUSH_FLAG is supplied by userspace and passed to the target through a new 'status_flags' parameter in the target's dm_status_fn. The userspace dmsetup tool will support the --noflush flag with the 'dmsetup status' and 'dmsetup wait' commands from version 1.02.76 onwards. Tested-by: Mike Snitzer Signed-off-by: Alasdair G Kergon

dm thin: add read only and fail io modes

2012-07-27T14:08:16+00:00

Add read-only and fail-io modes to thin provisioning. If a transaction commit fails the pool's metadata device will transition to "read-only" mode. If a commit fails once already in read-only mode the transition to "fail-io" mode occurs. Once in fail-io mode the pool and all associated thin devices will report a status of "Fail". Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon

dm thin: reduce number of metadata commits

2012-07-27T14:08:14+00:00

Reduce the number of metadata commits by using dm_thin_changed_this_transaction to check if metadata was changed on a per thin device granularity. Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon

dm thin metadata: add format option to dm_pool_metadata_open

2012-07-27T14:08:14+00:00

Add a parameter to dm_pool_metadata_open to indicate whether or not an unformatted metadata area should be formatted. Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon

dm: use bool bitfields in struct dm_target

2012-07-27T14:08:08+00:00

Use boolean bit fields for flags in struct dm_target. Signed-off-by: Alasdair G Kergon

dm thin: set flush_supported

2012-07-27T14:08:07+00:00

The thin provisioning target commits internal metadata on flush. So it should receive flushes regardless of whether the underlying devices support them. Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon

dm thin: avoid unnecessarily breaking sharing for flushes

2012-07-27T14:08:06+00:00

There's no need to break sharing, triggering a copy, for a write that has no data (i.e. a flush). Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon