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author | Matthew Wilcox <willy@infradead.org> | 2018-11-06 22:13:35 +0300 |
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committer | Matthew Wilcox <willy@infradead.org> | 2019-02-06 21:32:25 +0300 |
commit | 2fa044e51a1f35d7b04cbde07ec513b0ba195e38 (patch) | |
tree | ca7f9f39820ca4f8241caf7a6eef8f044db5d38a /block/blk-mq.h | |
parent | a3e4d3f97ec844de005a679585c04c5c03dfbdb6 (diff) | |
download | linux-2fa044e51a1f35d7b04cbde07ec513b0ba195e38.tar.xz |
XArray: Add cyclic allocation
This differs slightly from the IDR equivalent in five ways.
1. It can allocate up to UINT_MAX instead of being limited to INT_MAX,
like xa_alloc(). Also like xa_alloc(), it will write to the 'id'
pointer before placing the entry in the XArray.
2. The 'next' cursor is allocated separately from the XArray instead
of being part of the IDR. This saves memory for all the users which
do not use the cyclic allocation API and suits some users better.
3. It returns -EBUSY instead of -ENOSPC.
4. It will attempt to wrap back to the minimum value on memory allocation
failure as well as on an -EBUSY error, assuming that a user would
rather allocate a small ID than suffer an ID allocation failure.
5. It reports whether it has wrapped, which is important to some users.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Diffstat (limited to 'block/blk-mq.h')
0 files changed, 0 insertions, 0 deletions