NFSD: Clean up the nfsd_net::nfssvc_boot field

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There are two boot-time fields in struct nfsd_net: one called
boot_time and one called nfssvc_boot. The latter is used only to
form write verifiers, but its documenting comment declares:

        /* Time of server startup */

Since commit 27c438f53e ("nfsd: Support the server resetting the
boot verifier"), this field can be reset at any time; it's no
longer tied to server restart. So that comment is stale.

Also, according to pahole, struct timespec64 is 16 bytes long on
x86_64. The nfssvc_boot field is used only to form a write verifier,
which is 8 bytes long.

Let's clarify this situation by manufacturing an 8-byte verifier
in nfs_reset_boot_verifier() and storing only that in struct
nfsd_net.

We're grabbing 128 bits of time, so compress all of those into a
64-bit verifier instead of throwing out the high-order bits.
In the future, the siphash_key can be re-used for other hashed
objects per-nfsd_net.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

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This commit is contained in:

Chuck Lever 2021-12-29 14:43:16 -05:00

parent cdc556600c

commit 91d2e9b56c

3 changed files with 45 additions and 17 deletions

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8

fs/nfsd/netns.h

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3

fs/nfsd/nfsctl.c

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51

fs/nfsd/nfssvc.c

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