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Fixing ABD struct allocation for FreeBSD 

In the event we are allocating a gang ABD in FreeBSD we are passing 0
to abd_alloc_struct(); however, this led to an allocation of ABD scatter
with 0 chunks. This left the gang ABD allocation 24 bytes smaller than
it should have been.

Reviewed-by: Matt Macy <mmacy@FreeBSD.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Co-authored-by: Matt Macy <mmacy@FreeBSD.org>
Signed-off-by: Brian Atkinson <batkinson@lanl.gov>
Closes #10431
This commit is contained in:
Brian Atkinson 2020-06-16 11:05:22 -06:00 committed by GitHub
parent c13facb9c4
commit 0a03495e3e
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1 changed files with 13 additions and 4 deletions
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17
module/os/freebsd/zfs/abd_os.c
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@ -198,8 +198,15 @@ abd_t *
abd_alloc_struct(size_t size)
{
size_t chunkcnt = abd_chunkcnt_for_bytes(size);
size_t abd_size = offsetof(abd_t,
abd_u.abd_scatter.abd_chunks[chunkcnt]);
/*
* In the event we are allocating a gang ABD, the size passed in
* will be 0. We must make sure to set abd_size to the size of an
* ABD struct as opposed to an ABD scatter with 0 chunks. The gang
* ABD struct allocation accounts for an additional 24 bytes over
* a scatter ABD with 0 chunks.
*/
size_t abd_size = MAX(sizeof (abd_t),
offsetof(abd_t, abd_u.abd_scatter.abd_chunks[chunkcnt]));
abd_t *abd = kmem_alloc(abd_size, KM_PUSHPAGE);
ASSERT3P(abd, !=, NULL);
list_link_init(&abd->abd_gang_link);
@ -212,8 +219,10 @@ abd_alloc_struct(size_t size)
void
abd_free_struct(abd_t *abd)
{
size_t chunkcnt = abd_is_linear(abd) ? 0 : abd_scatter_chunkcnt(abd);
int size = offsetof(abd_t, abd_u.abd_scatter.abd_chunks[chunkcnt]);
size_t chunkcnt = abd_is_linear(abd) || abd_is_gang(abd) ? 0 :
abd_scatter_chunkcnt(abd);
int size = MAX(sizeof (abd_t),
offsetof(abd_t, abd_u.abd_scatter.abd_chunks[chunkcnt]));
mutex_destroy(&abd->abd_mtx);
ASSERT(!list_link_active(&abd->abd_gang_link));
kmem_free(abd, size);