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When opening an image with discard=off, we punch hole in the image when writing zeroes, making the image sparse. This breaks users that want to ensure that writes cannot fail with ENOSPACE by using fully allocated images[1]. bdrv_co_pwrite_zeroes() correctly disables BDRV_REQ_MAY_UNMAP if we opened the child without discard=unmap or discard=on. But we don't go through this function when accessing the top node. Move the check down to bdrv_co_do_pwrite_zeroes() which seems to be used in all code paths. This change implements the documented behavior, punching holes only when opening the image with discard=on or discard=unmap. This may not be the best default but can improve it later. The test depends on a file system supporting discard, deallocating the entire file when punching hole with the length of the entire file. Tested with xfs, ext4, and tmpfs. [1] https://lists.nongnu.org/archive/html/qemu-discuss/2024-06/msg00003.html Signed-off-by: Nir Soffer <nsoffer@redhat.com> Message-id: 20240628202058.1964986-3-nsoffer@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> |
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| data | ||
| decode | ||
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| fp | ||
| guest-debug | ||
| image-fuzzer | ||
| include | ||
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| dbus-vmstate-daemon.sh | ||
| Makefile.include | ||
| meson.build | ||
| test-qht-par.c | ||
| vhost-user-bridge.c | ||