On Thu, Nov 22, 2018 at 01:21:55PM +0100, Jan Kara wrote: > > Is there a reason for REQ_PRIO? I'm not sure all REQ_META reads are really > a priority ones... Hmm, good question. With the exception of readahead, most reads will be blocking some process. We are currently using REQ_PRIO for all directory block reads. The ext4_sb_read() function gets used for resizing, indirect block map to extent tree migration, and extended attribute reads. The last is the most common, and arguably the most justifiable to be REQ_PRIO. (Of course my understanding is that the block layer is ignoring REQ_PRIO, so this is mostly academic...) So I think what I'll do is this. I'll add a parameter to ext4_sb_read() so each caller can use use REQ_PRIO. REQ_PRIO will be used from xattr.c, but not from fs/ext4/migrate.c and fs/ext4/resize.c. - Ted
