nfsd: Implement NFSv4 FATTR4_CASE_INSENSITIVE and FATTR4_CASE_PRESERVING

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NFSD currently provides NFSv4 clients with hard-coded responses
indicating all exported filesystems are case-sensitive and
case-preserving. This is incorrect for case-insensitive filesystems
and ext4 directories with casefold enabled.

Query the underlying filesystem's actual case sensitivity via
nfsd_get_case_info() and return accurate values to clients. This
supports per-directory settings for filesystems that allow mixing
case-sensitive and case-insensitive directories within an export.

The helper queries the parent dentry for non-directory filehandles
because case-folding is a per-directory property. That resolution
has the same corner cases here as for NFSv3 PATHCONF: single-file
exports query an unexported parent, disconnected dentries report
defaults until reconnected, and hardlinked files track whichever
alias the dcache currently holds.

Reviewed-by: Roland Mainz <roland.mainz@nrubsig.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://patch.msgid.link/20260507-case-sensitivity-v14-14-e62cc8200435@oracle.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

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Chuck Lever 2026-05-07 04:53:07 -04:00 • committed by Christian Brauner

parent 211cb2ba48

commit 01ee7c3d2e

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fs/nfsd/nfs4xdr.c

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