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c33159dec7
This patch is purely mechanical, changing bool want_zero into an unsigned int for bitwise-or of flags. As of this patch, all implementations are unchanged (the old want_zero==true is now mode==BDRV_WANT_PRECISE which is a superset of BDRV_WANT_ZERO); but the callers in io.c that used to pass want_zero==false are now prepared for future driver changes that can now distinguish bewteen BDRV_WANT_ZERO vs. BDRV_WANT_ALLOCATED. The next patch will actually change the file-posix driver along those lines, now that we have more-specific hints. As for the background why this patch is useful: right now, the file-posix driver recognizes that if allocation is being queried, the entire image can be reported as allocated (there is no backing file to refer to) - but this throws away information on whether the entire image reads as zero (trivially true if lseek(SEEK_HOLE) at offset 0 returns -ENXIO, a bit more complicated to prove if the raw file was created with 'qemu-img create' since we intentionally allocate a small chunk of all-zero data to help with alignment probing). Later patches will add a generic algorithm for seeing if an entire file reads as zeroes. Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-ID: <20250509204341.3553601-16-eblake@redhat.com> |
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| accel | ||
| authz | ||
| block | ||
| chardev | ||
| crypto | ||
| disas | ||
| exec | ||
| fpu | ||
| gdbstub | ||
| hw | ||
| io | ||
| libdecnumber | ||
| migration | ||
| monitor | ||
| net | ||
| qapi | ||
| qemu | ||
| qobject | ||
| qom | ||
| scsi | ||
| semihosting | ||
| standard-headers | ||
| system | ||
| tcg | ||
| ui | ||
| user | ||
| elf.h | ||
| glib-compat.h | ||
| qemu-io.h | ||
| qemu-main.h | ||