diff options
| -rw-r--r-- | block/dirty-bitmap.c | 20 | ||||
| -rw-r--r-- | qapi/block-core.json | 34 |
2 files changed, 39 insertions, 15 deletions
diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c index e46f72b346..c6d4acebfa 100644 --- a/block/dirty-bitmap.c +++ b/block/dirty-bitmap.c @@ -29,12 +29,20 @@ #include "block/blockjob.h" /** - * A BdrvDirtyBitmap can be in three possible states: - * (1) successor is NULL and disabled is false: full r/w mode - * (2) successor is NULL and disabled is true: read only mode ("disabled") - * (3) successor is set: frozen mode. - * A frozen bitmap cannot be renamed, deleted, anonymized, cleared, set, - * or enabled. A frozen bitmap can only abdicate() or reclaim(). + * A BdrvDirtyBitmap can be in four possible user-visible states: + * (1) Active: successor is NULL, and disabled is false: full r/w mode + * (2) Disabled: successor is NULL, and disabled is true: qualified r/w mode, + * guest writes are dropped, but monitor writes are possible, + * through commands like merge and clear. + * (3) Frozen: successor is not NULL. + * A frozen bitmap cannot be renamed, deleted, cleared, set, + * enabled, merged to, etc. A frozen bitmap can only abdicate() + * or reclaim(). + * In this state, the anonymous successor bitmap may be either + * Active and recording writes from the guest (e.g. backup jobs), + * but it can be Disabled and not recording writes. + * (4) Locked: Whether Active or Disabled, the user cannot modify this bitmap + * in any way from the monitor. */ struct BdrvDirtyBitmap { QemuMutex *mutex; diff --git a/qapi/block-core.json b/qapi/block-core.json index b8c8e04d02..2b8afbb924 100644 --- a/qapi/block-core.json +++ b/qapi/block-core.json @@ -420,17 +420,27 @@ # # An enumeration of possible states that a dirty bitmap can report to the user. # -# @frozen: The bitmap is currently in-use by a backup operation or block job, -# and is immutable. -# -# @disabled: The bitmap is currently in-use by an internal operation and is -# read-only. It can still be deleted. +# @frozen: The bitmap is currently in-use by some operation and is immutable. +# If the bitmap was @active prior to the operation, new writes by the +# guest are being recorded in a temporary buffer, and will not be lost. +# Generally, bitmaps are cleared on successful use in an operation and +# the temporary buffer is committed into the bitmap. On failure, the +# temporary buffer is merged back into the bitmap without first +# clearing it. +# Please refer to the documentation for each bitmap-using operation, +# See also @blockdev-backup, @drive-backup. +# +# @disabled: The bitmap is not currently recording new writes by the guest. +# This is requested explicitly via @block-dirty-bitmap-disable. +# It can still be cleared, deleted, or used for backup operations. # # @active: The bitmap is actively monitoring for new writes, and can be cleared, # deleted, or used for backup operations. # -# @locked: The bitmap is currently in-use by some operation and can not be -# cleared, deleted, or used for backup operations. (Since 2.12) +# @locked: The bitmap is currently in-use by some operation and is immutable. +# If the bitmap was @active prior to the operation, it is still +# recording new writes. If the bitmap was @disabled, it is not +# recording new writes. (Since 2.12) # # Since: 2.4 ## @@ -2094,9 +2104,15 @@ # @block-dirty-bitmap-merge: # # Merge dirty bitmaps listed in @bitmaps to the @target dirty bitmap. -# The @bitmaps dirty bitmaps are unchanged. +# Dirty bitmaps in @bitmaps will be unchanged, except if it also appears +# as the @target bitmap. Any bits already set in @target will still be +# set after the merge, i.e., this operation does not clear the target. # On error, @target is unchanged. # +# The resulting bitmap will count as dirty any clusters that were dirty in any +# of the source bitmaps. This can be used to achieve backup checkpoints, or in +# simpler usages, to copy bitmaps. +# # Returns: nothing on success # If @node is not a valid block device, DeviceNotFound # If any bitmap in @bitmaps or @target is not found, GenericError @@ -2131,7 +2147,7 @@ ## # @x-debug-block-dirty-bitmap-sha256: # -# Get bitmap SHA256 +# Get bitmap SHA256. # # Returns: BlockDirtyBitmapSha256 on success # If @node is not a valid block device, DeviceNotFound |