Al Viro <viro@xxxxxxxxxxxxxxxxxx> writes: > On Sun, Apr 12, 2015 at 09:08:21PM +0400, Dmitry Monakhov wrote: >> Fix other long standing issues caused by fcntl(,F_SETFL,): >> - User can disable O_DIRECT for pipe[1] (paketized IO), but can not enable it again. >> - Currently we do not set O_APPEND on pipe[1] (IMHO it is wrong, but let it be) >> so it is reasonable to completely prohibit change O_APPEND flag on both >> end's of pipe. Add ->check_flags method in order to diallow O_APPEND toggling. >> >> Signed-off-by: Dmitry Monakhov <dmonakhov@xxxxxxxxxx> >> --- > > TBH, all those ->direct_IO != NULL checks seem to be a wrong approach. > If nothing else, it forces several filesystem into inventing a fake > ->direct_IO just to fool those tests. How about we > * introduce FMODE_MAY_DIRECT and allow ->open() explicitly set it > * make open_check_o_direct() and fcntl.c check that instead of poking > in ->f_mapping->a_ops, etc. > * provide a variant of generic_file_open() that would set that > bit and use it on the filesystems that handle dio 100% agree. FMODE is perfect place for that. BTW: I always wondering: why we do not mark pipe[1]->f_flags with O_APPEND? Probably the answer is that nobody care about ->f_flags since no_llseek returns -ESPIPE, but f_flags are visiable via fcntl so IMHO it is reasonable to fix that too. > -- > 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
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