29.03.2019 16:29, Andrey Shinkevich wrote: > A caller of the function bdrv_is_allocated_above() may want to > include the base node in the search. It is useful when we have > parallel commit/stream jobs on the same backing image chain. The > base node may be a top one of a parallel job at the same time > and go away before the first job completed. Instead of base, pass > the node that has the base as its backing one to the new function > bdrv_is_allocated_above_inclusive() to manage the issue.
I think it would be enough to say that it be used in following patch to drop dependence on base from block-stream job. > > Suggested-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com> > Signed-off-by: Andrey Shinkevich <andrey.shinkev...@virtuozzo.com> > --- > block/io.c | 39 ++++++++++++++++++++++++++++++++++----- > include/block/block.h | 5 ++++- > 2 files changed, 38 insertions(+), 6 deletions(-) > > diff --git a/block/io.c b/block/io.c > index dfc153b..8b273e5 100644 > --- a/block/io.c > +++ b/block/io.c > @@ -2317,7 +2317,8 @@ int coroutine_fn bdrv_is_allocated(BlockDriverState > *bs, int64_t offset, > * Given an image chain: ... -> [BASE] -> [INTER1] -> [INTER2] -> [TOP] > * > * Return true if (a prefix of) the given range is allocated in any image > - * between BASE and TOP (inclusive). BASE can be NULL to check if the given > + * between BASE and TOP (TOP included). To check the BASE image, set the > + * 'base_included' to 'true'. The BASE can be NULL to check if the given > * offset is allocated in any image of the chain. Return false otherwise, > * or negative errno on failure. > * > @@ -2329,16 +2330,21 @@ int coroutine_fn bdrv_is_allocated(BlockDriverState > *bs, int64_t offset, > * but 'pnum' will only be 0 when end of file is reached. > * > */ > -int bdrv_is_allocated_above(BlockDriverState *top, > - BlockDriverState *base, > - int64_t offset, int64_t bytes, int64_t *pnum) > +static int bdrv_do_is_allocated_above(BlockDriverState *top, > + BlockDriverState *base, > + bool base_included, int64_t offset, > + int64_t bytes, int64_t *pnum) > { > BlockDriverState *intermediate; > int ret; > int64_t n = bytes; > + bool exit_loop = top == base ? true : false; > + /* Sanity check */ > + base_included = base ? base_included : false; > + bool include_node = top == base ? base_included : true; > > intermediate = top; > - while (intermediate && intermediate != base) { > + while (intermediate && include_node) { > int64_t pnum_inter; > int64_t size_inter; > > @@ -2361,12 +2367,35 @@ int bdrv_is_allocated_above(BlockDriverState *top, > } > > intermediate = backing_bs(intermediate); > + include_node = intermediate != base; > + if (exit_loop) { > + include_node = false; > + } else if (!include_node && base_included) { > + /* Iterate once more */ > + include_node = true; > + exit_loop = true; > + } how about this, without additional variables: -int bdrv_is_allocated_above(BlockDriverState *top, - BlockDriverState *base, - int64_t offset, int64_t bytes, int64_t *pnum) +static int bdrv_do_is_allocated_above(BlockDriverState *top, + BlockDriverState *base, + bool base_included, int64_t offset, + int64_t bytes, int64_t *pnum) { BlockDriverState *intermediate; int ret; int64_t n = bytes; intermediate = top; - while (intermediate && intermediate != base) { + while (base_included || intermediate != base) { int64_t pnum_inter; int64_t size_inter; @@ -2360,6 +2361,11 @@ int bdrv_is_allocated_above(BlockDriverState *top, n = pnum_inter; } + if (intermediate == base) { + assert(!base_included); + break; + } + intermediate = backing_bs(intermediate); } > } > > *pnum = n; > return 0; > } > > +int bdrv_is_allocated_above(BlockDriverState *top, > + BlockDriverState *base, > + int64_t offset, int64_t bytes, int64_t *pnum) > +{ > + return bdrv_do_is_allocated_above(top, base, false, offset, bytes, pnum); > +} > + > +int bdrv_is_allocated_above_inclusive(BlockDriverState *top, > + BlockDriverState *base, > + int64_t offset, int64_t bytes, > + int64_t *pnum) > +{ > + return bdrv_do_is_allocated_above(top, base, true, offset, bytes, pnum); > +} > + > typedef struct BdrvVmstateCo { > BlockDriverState *bs; > QEMUIOVector *qiov; > diff --git a/include/block/block.h b/include/block/block.h > index c7a2619..a7846d9 100644 > --- a/include/block/block.h > +++ b/include/block/block.h > @@ -448,7 +448,10 @@ int bdrv_is_allocated(BlockDriverState *bs, int64_t > offset, int64_t bytes, > int64_t *pnum); > int bdrv_is_allocated_above(BlockDriverState *top, BlockDriverState *base, > int64_t offset, int64_t bytes, int64_t *pnum); > - > +int bdrv_is_allocated_above_inclusive(BlockDriverState *top, > + BlockDriverState *base, > + int64_t offset, int64_t bytes, > + int64_t *pnum); > bool bdrv_is_read_only(BlockDriverState *bs); > int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only, > bool ignore_allow_rdw, Error **errp); > -- Best regards, Vladimir