/qemu/ |
H A D | qemu-img.c | e0b371ed Mon Jun 11 21:39:26 GMT 2018 Eric Blake <eblake@redhat.com> qemu-img: Fix assert when mapping unaligned raw file
Commit a290f085 exposed a latent bug in qemu-img map introduced during the conversion of block status to be byte-based. Earlier in commit 5e344dd8, the internal interface get_block_status() switched to take byte-based parameters, but still called a sector-based block layer function; as such, rounding was added in the lone caller to obey the contract. However, commit 237d78f8 changed get_block_status() to truly be byte-based, at which point rounding to sector boundaries can result in calling bdrv_block_status() with 'bytes == 0' (a coding error) when the boundary between data and a hole falls mid-sector (true for the past-EOF implicit hole present in POSIX files). Fix things by removing the rounding that is now no longer necessary.
See also https://bugzilla.redhat.com/1589738
Fixes: 237d78f8 Reported-by: Dan Kenigsberg <danken@redhat.com> Reported-by: Nir Soffer <nsoffer@redhat.com> Reported-by: Maor Lipchuk <mlipchuk@redhat.com> CC: qemu-stable@nongnu.org Signed-off-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com> e0b371ed Mon Jun 11 21:39:26 GMT 2018 Eric Blake <eblake@redhat.com> qemu-img: Fix assert when mapping unaligned raw file
Commit a290f085 exposed a latent bug in qemu-img map introduced during the conversion of block status to be byte-based. Earlier in commit 5e344dd8, the internal interface get_block_status() switched to take byte-based parameters, but still called a sector-based block layer function; as such, rounding was added in the lone caller to obey the contract. However, commit 237d78f8 changed get_block_status() to truly be byte-based, at which point rounding to sector boundaries can result in calling bdrv_block_status() with 'bytes == 0' (a coding error) when the boundary between data and a hole falls mid-sector (true for the past-EOF implicit hole present in POSIX files). Fix things by removing the rounding that is now no longer necessary.
See also https://bugzilla.redhat.com/1589738
Fixes: 237d78f8 Reported-by: Dan Kenigsberg <danken@redhat.com> Reported-by: Nir Soffer <nsoffer@redhat.com> Reported-by: Maor Lipchuk <mlipchuk@redhat.com> CC: qemu-stable@nongnu.org Signed-off-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com> 237d78f8 Thu Oct 12 03:47:03 GMT 2017 Eric Blake <eblake@redhat.com> block: Convert bdrv_get_block_status() to bytes
We are gradually moving away from sector-based interfaces, towards byte-based. In the common case, allocation is unlikely to ever use values that are not naturally sector-aligned, but it is possible that byte-based values will let us be more precise about allocation at the end of an unaligned file that can do byte-based access.
Changing the name of the function from bdrv_get_block_status() to bdrv_block_status() ensures that the compiler enforces that all callers are updated. For now, the io.c layer still assert()s that all callers are sector-aligned, but that can be relaxed when a later patch implements byte-based block status in the drivers.
There was an inherent limitation in returning the offset via the return value: we only have room for BDRV_BLOCK_OFFSET_MASK bits, which means an offset can only be mapped for sector-aligned queries (or, if we declare that non-aligned input is at the same relative position modulo 512 of the answer), so the new interface also changes things to return the offset via output through a parameter by reference rather than mashed into the return value. We'll have some glue code that munges between the two styles until we finish converting all uses.
For the most part this patch is just the addition of scaling at the callers followed by inverse scaling at bdrv_block_status(), coupled with the tweak in calling convention. But some code, particularly bdrv_is_allocated(), gets a lot simpler because it no longer has to mess with sectors.
For ease of review, bdrv_get_block_status_above() will be tackled separately.
Signed-off-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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/qemu/block/ |
H A D | qcow2-cluster.c | 237d78f8 Thu Oct 12 03:47:03 GMT 2017 Eric Blake <eblake@redhat.com> block: Convert bdrv_get_block_status() to bytes
We are gradually moving away from sector-based interfaces, towards byte-based. In the common case, allocation is unlikely to ever use values that are not naturally sector-aligned, but it is possible that byte-based values will let us be more precise about allocation at the end of an unaligned file that can do byte-based access.
Changing the name of the function from bdrv_get_block_status() to bdrv_block_status() ensures that the compiler enforces that all callers are updated. For now, the io.c layer still assert()s that all callers are sector-aligned, but that can be relaxed when a later patch implements byte-based block status in the drivers.
There was an inherent limitation in returning the offset via the return value: we only have room for BDRV_BLOCK_OFFSET_MASK bits, which means an offset can only be mapped for sector-aligned queries (or, if we declare that non-aligned input is at the same relative position modulo 512 of the answer), so the new interface also changes things to return the offset via output through a parameter by reference rather than mashed into the return value. We'll have some glue code that munges between the two styles until we finish converting all uses.
For the most part this patch is just the addition of scaling at the callers followed by inverse scaling at bdrv_block_status(), coupled with the tweak in calling convention. But some code, particularly bdrv_is_allocated(), gets a lot simpler because it no longer has to mess with sectors.
For ease of review, bdrv_get_block_status_above() will be tackled separately.
Signed-off-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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H A D | io.c | 237d78f8 Thu Oct 12 03:47:03 GMT 2017 Eric Blake <eblake@redhat.com> block: Convert bdrv_get_block_status() to bytes
We are gradually moving away from sector-based interfaces, towards byte-based. In the common case, allocation is unlikely to ever use values that are not naturally sector-aligned, but it is possible that byte-based values will let us be more precise about allocation at the end of an unaligned file that can do byte-based access.
Changing the name of the function from bdrv_get_block_status() to bdrv_block_status() ensures that the compiler enforces that all callers are updated. For now, the io.c layer still assert()s that all callers are sector-aligned, but that can be relaxed when a later patch implements byte-based block status in the drivers.
There was an inherent limitation in returning the offset via the return value: we only have room for BDRV_BLOCK_OFFSET_MASK bits, which means an offset can only be mapped for sector-aligned queries (or, if we declare that non-aligned input is at the same relative position modulo 512 of the answer), so the new interface also changes things to return the offset via output through a parameter by reference rather than mashed into the return value. We'll have some glue code that munges between the two styles until we finish converting all uses.
For the most part this patch is just the addition of scaling at the callers followed by inverse scaling at bdrv_block_status(), coupled with the tweak in calling convention. But some code, particularly bdrv_is_allocated(), gets a lot simpler because it no longer has to mess with sectors.
For ease of review, bdrv_get_block_status_above() will be tackled separately.
Signed-off-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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/qemu/include/block/ |
H A D | block.h | 237d78f8 Thu Oct 12 03:47:03 GMT 2017 Eric Blake <eblake@redhat.com> block: Convert bdrv_get_block_status() to bytes
We are gradually moving away from sector-based interfaces, towards byte-based. In the common case, allocation is unlikely to ever use values that are not naturally sector-aligned, but it is possible that byte-based values will let us be more precise about allocation at the end of an unaligned file that can do byte-based access.
Changing the name of the function from bdrv_get_block_status() to bdrv_block_status() ensures that the compiler enforces that all callers are updated. For now, the io.c layer still assert()s that all callers are sector-aligned, but that can be relaxed when a later patch implements byte-based block status in the drivers.
There was an inherent limitation in returning the offset via the return value: we only have room for BDRV_BLOCK_OFFSET_MASK bits, which means an offset can only be mapped for sector-aligned queries (or, if we declare that non-aligned input is at the same relative position modulo 512 of the answer), so the new interface also changes things to return the offset via output through a parameter by reference rather than mashed into the return value. We'll have some glue code that munges between the two styles until we finish converting all uses.
For the most part this patch is just the addition of scaling at the callers followed by inverse scaling at bdrv_block_status(), coupled with the tweak in calling convention. But some code, particularly bdrv_is_allocated(), gets a lot simpler because it no longer has to mess with sectors.
For ease of review, bdrv_get_block_status_above() will be tackled separately.
Signed-off-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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