On Mon, Jul 06, 2009 at 11:08:04AM +0200, Nick Piggin wrote: > OK, hmm, but I wonder -- most of the time do_truncate will need to > call notify_change anyway, so I wonder if avoiding the double > indirection saves us anything? (It requires 2 indirect calls either > way). And if we call ->setsize from ->setattr, then a filesystem > which implements its own ->setattr could avoid one of those indirect > calls. Not so if do_truncate has to call ->setattr then ->setsize. I don't quite understand what you mean here. In the end there should be one single indirect call, ->setsize (or whatever it's called by then). In the first round we'd split up a helper just for size updates from notify_change, ala: int vfs_truncate(struct dentry *dentry, loff_t size, int flags, file) { int error; error = security_inode_truncate(dentry, size, flags, file); if (error) return error; if (inode->i_op->setsize) { inode->i_op->setsize(dentry, size, flags, file); } else { <... built up iattr here ...> if (inode->i_op->setattr) { down_write(&dentry->d_inode->i_alloc_sem); error = inode->i_op->setattr(dentry, attr); up_write(&dentry->d_inode->i_alloc_sem); } else { down_write(&dentry->d_inode->i_alloc_sem); error = inode_setattr(inode, attr); up_write(&dentry->d_inode->i_alloc_sem); } } if (!error) fsnotify_truncate(dentry, size, flags); return error; } One all filesistem are converted to have a setsize method (either their own or simple_setsize) the !inode->i_op->setsize case can go away. Note that the above variant moves taking i_alloc_sem into ->setsize as it's not required for most filesystems (I think only extN need for O_DIRECT). Also the above doesn't deal with killing the SUID/SGID bits yet, we'll need some good way for that. Actually it might be better to just pass the iattr to ->setsize to so we can have the parsing for those arguments once, and that filesystems can re-use parts of their ->setattr for ->setsize if it's complex enough (timestamp updates and suid/sgid killing) -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html