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| author | Peter Maydell <peter.maydell@linaro.org> | 2018-02-13 19:57:46 +0000 |
|---|---|---|
| committer | Peter Maydell <peter.maydell@linaro.org> | 2018-02-13 19:57:46 +0000 |
| commit | 685a4eaf6d552762e03ce02b136978e0e5d5a0c2 (patch) | |
| tree | eec399b0812b0bf844abc6c75efbd3c6b0be60c9 /docs | |
| parent | bec9c64ef7be8063f1192608b83877bc5c9ea217 (diff) | |
| parent | 0a4dc980e6c935e9be745ce3ee1a4c71629ecd00 (diff) | |
Merge remote-tracking branch 'remotes/kevin/tags/for-upstream' into staging
Block layer patches
# gpg: Signature made Tue 13 Feb 2018 17:03:11 GMT
# gpg: using RSA key 7F09B272C88F2FD6
# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>"
# Primary key fingerprint: DC3D EB15 9A9A F95D 3D74 56FE 7F09 B272 C88F 2FD6
* remotes/kevin/tags/for-upstream: (55 commits)
iotests: Add l2-cache-entry-size to iotest 137
iotests: Test downgrading an image using a small L2 slice size
iotests: Test valid values of l2-cache-entry-size
qcow2: Allow configuring the L2 slice size
qcow2: Rename l2_table in count_cow_clusters()
qcow2: Rename l2_table in count_contiguous_clusters_unallocated()
qcow2: Rename l2_table in count_contiguous_clusters()
qcow2: Rename l2_table in qcow2_alloc_compressed_cluster_offset()
qcow2: Update qcow2_truncate() to support L2 slices
qcow2: Update expand_zero_clusters_in_l1() to support L2 slices
qcow2: Prepare expand_zero_clusters_in_l1() for adding L2 slice support
qcow2: Read refcount before L2 table in expand_zero_clusters_in_l1()
qcow2: Update qcow2_update_snapshot_refcount() to support L2 slices
qcow2: Prepare qcow2_update_snapshot_refcount() for adding L2 slice support
qcow2: Update zero_single_l2() to support L2 slices
qcow2: Update discard_single_l2() to support L2 slices
qcow2: Update handle_alloc() to support L2 slices
qcow2: Update handle_copied() to support L2 slices
qcow2: Update qcow2_alloc_cluster_link_l2() to support L2 slices
qcow2: Update qcow2_get_cluster_offset() to support L2 slices
...
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/qemu-block-drivers.texi | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/docs/qemu-block-drivers.texi b/docs/qemu-block-drivers.texi index cd74767ed3..f1793692bb 100644 --- a/docs/qemu-block-drivers.texi +++ b/docs/qemu-block-drivers.texi @@ -845,6 +845,16 @@ QEMU transparently handles lock handover during shared storage migration. For shared virtual disk images between multiple VMs, the "share-rw" device option should be used. +By default, the guest has exclusive write access to its disk image. If the +guest can safely share the disk image with other writers the @code{-device +...,share-rw=on} parameter can be used. This is only safe if the guest is +running software, such as a cluster file system, that coordinates disk accesses +to avoid corruption. + +Note that share-rw=on only declares the guest's ability to share the disk. +Some QEMU features, such as image file formats, require exclusive write access +to the disk image and this is unaffected by the share-rw=on option. + Alternatively, locking can be fully disabled by "locking=off" block device option. In the command line, the option is usually in the form of "file.locking=off" as the protocol driver is normally placed as a "file" child |