| title: | Too many security check reads to getxattr |
|
Im investigating a performance degradation in yaffs when xattribs are
enabled. Yes, I know yaffs is not part of mainline Linux yet, but this is
really a vfs question.
What I notice is that on every write the "security.capability" xattribute gets
checked. Surely once the vfs has tried reading this once it should not try
again on every write.
Herewith a call stack
[ 2317.288740] [<f85b3b17 ] yaffs_getxattr+0x27/0xa0 [yaffs2]
[ 2317.288746] [<f85b3af0 ] ? yaffs_getxattr+0x0/0xa0 [yaffs2]
[ 2317.288750] [<c03091c7 ] cap_inode_need_killpriv+0x37/0x50
[ 2317.288753] [<c030a434 ] security_inode_need_killpriv+0x14/0x20
[ 2317.288757] [<c01dda2d ] file_remove_suid+0x1d/0x60
[ 2317.288761] [<c01dfd8a ] __generic_file_aio_write+0x25a/0x550
[ 2317.288764] [<c0229eef ] ? link_path_walk+0x42f/0x9b0
[ 2317.288768] [<c023075f ] ? dput+0x6f/0xd0
[ 2317.288772] [<c01e00d8 ] generic_file_aio_write+0x58/0xc0
[ 2317.288775] [<c021e819 ] do_sync_write+0xb9/0xf0
[ 2317.288779] [<c0222954 ] ? cp_new_stat64+0xe4/0x100
[ 2317.288783] [<c0338346 ] ? apparmor_file_permission+0x16/0x20
[ 2317.288786] [<c030ba4d ] ? security_file_permission+0x1d/0x80
[ 2317.288790] [<c021e9b1 ] ? rw_verify_area+0x71/0xe0
[ 2317.288793] [<c021eabb ] vfs_write+0x9b/0x160
[ 2317.288796] [<c021e760 ] ? do_sync_write+0x0/0xf0
[ 2317.288800] [<c021f4a2 ] sys_write+0x42/0x70
[ 2317.288803] [<c0102cdf ] sysenter_do_call+0x12/0x28
[ 2317.288806] yaffs_getxattr "security.capability" from object 257
Any hints as to why this is happening and how to stop this from happening?
Thanks
-- Charles
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