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authorDavid Howells <dhowells@redhat.com>2020-12-23 10:39:57 +0000
committerDavid Howells <dhowells@redhat.com>2021-01-04 12:25:19 +0000
commit366911cd762db02c2dd32fad1be96b72a66f205d (patch)
treef09fdfc5d7c4d61dfb2fd936dc0f5a1a107db1fd /fs/afs/dir_edit.c
parent26982a89cad77c0efc1c0c79bee0e3d75e9281d4 (diff)
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 <dhowells@redhat.com> Tested-by: Marc Dionne <marc.dionne@auristor.com>
Diffstat (limited to 'fs/afs/dir_edit.c')
-rw-r--r--fs/afs/dir_edit.c6
1 files changed, 2 insertions, 4 deletions
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];