ksmbd: send inline FinderInfo in FIND responses when READDIR_ATTR negotiated

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Without READDIR_ATTR, macOS Finder resolves type/creator/icon for
every file in a directory listing by opening its AFP_AfpInfo stream
individually -- one extra CREATE+QUERY_INFO+CLOSE round trip per file,
which is the dominant cost of browsing a large directory over SMB from
a Mac.

When the client negotiates READDIR_ATTR (conn->aapl_readdir_attr, set
during CREATE's AAPL context exchange), inline the same information
directly into each FILEID_BOTH_DIRECTORY_INFORMATION FIND entry:
  EaSize           = max_access, expanded specific rights
                      (GENERIC_ALL_FLAGS), not the raw FILE_GENERIC_ALL_LE
                      "generic" meta-bit -- that bit has none of the
                      specific FILE_* rights macOS's smbfs.kext checks
                      bit-by-bit, so reporting it directly would fail
                      every access check and show Finder's "no entry"
                      badge on every file/folder.
  ShortNameLength  = 24 (fixed; the spec says 0 when there's no short
                      name; kept for wire parity with reference server,
                      see below)
  ShortName[0..7]  = resource fork size (0 -- no resource forks)
  ShortName[8..23] = compressed FinderInfo (all zero: type/creator
                      unset, client falls back to extension-based
                      icon/type detection, consistent with the
                      AFP_AfpInfo synthesis this mirrors)
  Reserved2        = Unix mode bits
Reparse-point status is still carried via ExtFileAttributes rather
than EaSize once READDIR_ATTR is active, since EaSize is repurposed
for max_access.

Reverse-engineered from macOS smbfs.kext network behavior and cross-checked
against reference implementation marshalling (reference implementation
behavior). Also confirmed against AAPL's published public client behavior
(public client behavior reference) -- every field here matches exactly,
except ShortNameLength=24: real V1 clients read but never examine that
field, so it's kept for wire parity with reference server, not because
macOS requires it.

Assisted-by: Claude:claude-sonnet-5
Signed-off-by: Gael Blivet <gael.blivet@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>

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This commit is contained in:

Gael Blivet 2026-07-10 08:38:14 +09:00 • committed by Namjae Jeon

parent eaff8e924f

commit 9dfb281383

1 changed files with 53 additions and 5 deletions

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fs/smb/server/smb2pdu.c

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