Konstantin Belousov ca39f23347 ufs: do not leave around empty buffers shadowing disk content ... If the ffs_write() operation specified to overwrite the whole buffer, ffs tries to save the read by not validating allocated buffer. Then uiommove() might fail with EFAULT, in which case pages are left zeroed and marked valid but not read from the disk. Then vn_io_fault() logic retries the write after holding the user pages to avoid EFAULTs. In erronous case of really faulty buffer, or in contrived case of writing from file to itself, we are left with zeroed buffer instead of valid content written back to disk. Handle the situation by releasing non-cached buffer on fault, instead of clearing it. Note that buffers with alive dependencies cannot be released, but also either they cannot have valid content on the disk because dependency on data buffer means that it was not yet written, or they were reallocated by fragment extension or ffs_reallocbks(), and are already fully valid. Reported by: kevans Discussed with: mav In collaboration with: pho Sponsored by: The FreeBSD Foundation MFC after: 1 week		2023-12-16 00:06:10 +02:00
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ffs	ufs: do not leave around empty buffers shadowing disk content	2023-12-16 00:06:10 +02:00
ufs	Increase UFS/FFS maximum link count from 32767 to 65530.	2023-12-03 12:40:29 -08:00