[libvirt] [PATCH 0/3] Support --allocate and --shrink for vol-resize

https://bugzilla.redhat.com/show_bug.cgi?id=804516 Though the bug's title is about the document, but I prefer to implement it instead of changing document. Those two flags were added long time ago, but never implemented, it's not good to say they are not supported now while they were already exposed outside. A few examples of vol-resize with the patches: 1) Create 5M a parse vol % dd of=/var/lib/libvirt/images/sparse.raw bs=1k seek=5120 count=0 0+0 records in 0+0 records out 0 bytes (0 B) copied, 7.904e-06 s, 0.0 kB/s % ./tools/virsh pool-refresh default Pool default refreshed %s ./tools/virsh vol-info /var/lib/libvirt/images/sparse.raw Name: sparse.raw Type: file Capacity: 5.00 MiB Allocation: 0.00 B 2) Resize the vol to 6M with --allocate, I.E. The capacity (5M - 6M) is preallocated. % ./tools/virsh vol-resize /var/lib/libvirt/images/sparse.raw 6M --allocate Size of volume 'sparse.raw' successfully changed to 6M % ./tools/virsh vol-info /var/lib/libvirt/images/sparse.raw Name: sparse.raw Type: file Capacity: 6.00 MiB Allocation: 1.00 MiB 3) Resize the vol to 7M without --allocate. I.E. The new 1M capacity (6M - 7M) is sparse. % ./tools/virsh vol-resize /var/lib/libvirt/images/sparse.raw 7M Size of volume 'sparse.raw' successfully changed to 7M %s ./tools/virsh vol-info /var/lib/libvirt/images/sparse.raw Name: sparse.raw Type: file Capacity: 7.00 MiB Allocation: 1.00 MiB 3) Resize the vol to 8M with --allocate, I.E. The new 1 M capacity (7M - 8M) is preallocated % ./tools/virsh vol-resize /var/lib/libvirt/images/sparse.raw 8M --allocate Size of volume 'sparse.raw' successfully changed to 8M % ./tools/virsh vol-info /var/lib/libvirt/images/sparse.raw Name: sparse.raw Type: file Capacity: 8.00 MiB Allocation: 2.00 MiB ====== Now the parse file's allocation is like: 0 5 6 7 8 ----------------------------------------------------------------- | zero | allocated | zero | allocated | ----------------------------------------------------------------- %s ./tools/virsh vol-resize /var/lib/libvirt/images/sparse.raw 6M --shrink Size of volume 'sparse.raw' successfully changed to 6M %s ./tools/virsh vol-info /var/lib/libvirt/images/sparse.raw Name: sparse.raw Type: file Capacity: 6.00 MiB Allocation: 1.00 MiB ===== The vol still get 1M preallocate space kept, expected. Osier Yang (3): storage: Support preallocate the new capacity for vol-resize storage: Forbid to shrink the vol's capacity if no --shrink is specified storage: Allow --shrink for raw type volume of fs pool src/storage/storage_backend_fs.c | 22 ++++++++++++++++++---- src/storage/storage_driver.c | 12 +++++++++++- src/util/virstoragefile.c | 39 ++++++++++++++++++++++++++++++++++++--- src/util/virstoragefile.h | 6 +++++- 4 files changed, 70 insertions(+), 9 deletions(-) -- 1.8.1.4