NFSv4.2: Rework scratch handling for READ_PLUS (again)

[ Upstream commit 303a780520 ]

I found that the read code might send multiple requests using the same
nfs_pgio_header, but nfs4_proc_read_setup() is only called once. This is
how we ended up occasionally double-freeing the scratch buffer, but also
means we set a NULL pointer but non-zero length to the xdr scratch
buffer. This results in an oops the first time decoding needs to copy
something to scratch, which frequently happens when decoding READ_PLUS
hole segments.

I fix this by moving scratch handling into the pageio read code. I
provide a function to allocate scratch space for decoding read replies,
and free the scratch buffer when the nfs_pgio_header is freed.

Fixes: fbd2a05f29 (NFSv4.2: Rework scratch handling for READ_PLUS)
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Anna Schumaker 2023-06-09 15:26:25 -04:00 • committed by Greg Kroah-Hartman
commit a2f4cb206b
5 changed files with 14 additions and 13 deletions