The number of dirent records used by an AFS directory entry should be
calculated using the assumption that there is a 16-byte name field in the
first block, rather than a 20-byte name field (which is actually the case).
This miscalculation is historic and effectively standard, so we have to use
it.
The calculation we need to use is:
1 + (((strlen(name) + 1) + 15) >> 5)
where we are adding one to the strlen() result to account for the NUL
termination.
Fix this by the following means:
(1) Create an inline function to do the calculation for a given name
length.
(2) Use the function to calculate the number of records used for a dirent
in afs_dir_iterate_block().
Use this to move the over-end check out of the loop since it only
needs to be done once.
Further use this to only go through the loop for the 2nd+ records
composing an entry. The only test there now is for if the record is
allocated - and we already checked the first block at the top of the
outer loop.
(3) Add a max name length check in afs_dir_iterate_block().
(4) Make afs_edit_dir_add() and afs_edit_dir_remove() use the function
from (1) to calculate the number of blocks rather than doing it
incorrectly themselves.
Fixes: 63a4681ff3 ("afs: Locally edit directory data for mkdir/create/unlink/...")
Fixes: ^1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Marc Dionne <marc.dionne@auristor.com>
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