linux: Bound native getdents and getdents64 batchesHEADmain

linux_getdents() and linux_getdents64() round their native read size up
to DEV_BSIZE before converting entries. For an unaligned caller buffer,
the native batch can contain more entries than fit in the Linux buffer.
Conversion then returns EINVAL even after copying complete entries,
and the native read has already advanced the directory position.

For counts of at least DEV_BSIZE, use min(args->count, MAXBSIZE) instead.
A 768-byte request, such as rustix's initial directory read, now uses a
768-byte native buffer rather than 1024. The converted Linux dirent and
dirent64 records are no larger than their native counterparts, so the
whole translated batch fits. Returning a short batch is allowed, and
consuming the whole native batch avoids needing to rewind the directory
position.

Keep the existing sizing for counts below DEV_BSIZE. This fixes the
oversized-batch case in both getdents interfaces, including legacy
getdents for 32-bit and 64-bit callers. The remaining small-buffer,
copyout-failure and old single-entry readdir problems are outside the
scope of this change.

Fixes:	110f2567cb51 ("linux_file.c: Fix handling of NFS [...]")
MFC after:	3 days
Sponsored by:	Alchemilla Ventures Private Limited
Reviewed by:	kevans, markj
Differential Revision:	https://reviews.freebsd.org/D60760

0 files changed, 0 insertions, 0 deletions