From 366911cd762db02c2dd32fad1be96b72a66f205d Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 23 Dec 2020 10:39:57 +0000 Subject: afs: Fix directory entry size calculation 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: 63a4681ff39c ("afs: Locally edit directory data for mkdir/create/unlink/...") Fixes: ^1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: David Howells Tested-by: Marc Dionne --- fs/afs/dir_edit.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'fs/afs/dir_edit.c') diff --git a/fs/afs/dir_edit.c b/fs/afs/dir_edit.c index 2ffe09abae7f..f4600c1353ad 100644 --- a/fs/afs/dir_edit.c +++ b/fs/afs/dir_edit.c @@ -215,8 +215,7 @@ void afs_edit_dir_add(struct afs_vnode *vnode, } /* Work out how many slots we're going to need. */ - need_slots = round_up(12 + name->len + 1 + 4, AFS_DIR_DIRENT_SIZE); - need_slots /= AFS_DIR_DIRENT_SIZE; + need_slots = afs_dir_calc_slots(name->len); meta_page = kmap(page0); meta = &meta_page->blocks[0]; @@ -393,8 +392,7 @@ void afs_edit_dir_remove(struct afs_vnode *vnode, } /* Work out how many slots we're going to discard. */ - need_slots = round_up(12 + name->len + 1 + 4, AFS_DIR_DIRENT_SIZE); - need_slots /= AFS_DIR_DIRENT_SIZE; + need_slots = afs_dir_calc_slots(name->len); meta_page = kmap(page0); meta = &meta_page->blocks[0]; -- cgit v1.2.3