On Wed, Jul 29, 2020 at 04:12:22PM +0200, Martin Kepplinger wrote: > On 28.07.20 22:02, Alan Stern wrote: > > On Tue, Jul 28, 2020 at 09:02:44AM +0200, Martin Kepplinger wrote: > >> Hi Alan, > >> > >> Any API cleanup is of course welcome. I just wanted to remind you that > >> the underlying problem: broken block device runtime pm. Your initial > >> proposed fix "almost" did it and mounting works but during file access, > >> it still just looks like a runtime_resume is missing somewhere. > > > > Well, I have tested that proposed fix several times, and on my system > > it's working perfectly. When I stop accessing a drive it autosuspends, > > and when I access it again it gets resumed and works -- as you would > > expect. > > that's weird. when I mount, everything looks good, "sda1". But as soon > as I cd to the mountpoint and do "ls" (on another SD card "ls" works but > actual file reading leads to the exact same errors), I get: > > [ 77.474632] sd 0:0:0:0: [sda] tag#0 UNKNOWN(0x2003) Result: > hostbyte=0x00 driverbyte=0x08 cmd_age=0s > [ 77.474647] sd 0:0:0:0: [sda] tag#0 Sense Key : 0x6 [current] > [ 77.474655] sd 0:0:0:0: [sda] tag#0 ASC=0x28 ASCQ=0x0 > [ 77.474667] sd 0:0:0:0: [sda] tag#0 CDB: opcode=0x28 28 00 00 00 60 > 40 00 00 01 00 This error report comes from the SCSI layer, not the block layer. > [ 77.474678] blk_update_request: I/O error, dev sda, sector 24640 op > 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0 > [ 77.485836] sd 0:0:0:0: [sda] tag#0 device offline or changed > [ 77.491628] blk_update_request: I/O error, dev sda, sector 24641 op > 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0 > [ 77.502275] sd 0:0:0:0: [sda] tag#0 device offline or changed > [ 77.508051] blk_update_request: I/O error, dev sda, sector 24642 op > 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0 > [ 77.518651] sd 0:0:0:0: [sda] tag#0 device offline or changed > (...) > [ 77.947653] sd 0:0:0:0: [sda] tag#0 device offline or changed > [ 77.953434] FAT-fs (sda1): Directory bread(block 16448) failed > [ 77.959333] sd 0:0:0:0: [sda] tag#0 device offline or changed > [ 77.965118] FAT-fs (sda1): Directory bread(block 16449) failed > [ 77.971014] sd 0:0:0:0: [sda] tag#0 device offline or changed > [ 77.976802] FAT-fs (sda1): Directory bread(block 16450) failed > [ 77.982698] sd 0:0:0:0: [sda] tag#0 device offline or changed > (...) > [ 78.384929] FAT-fs (sda1): Filesystem has been set read-only > [ 103.070973] sd 0:0:0:0: [sda] tag#0 device offline or changed > [ 103.076751] print_req_error: 118 callbacks suppressed > [ 103.076760] blk_update_request: I/O error, dev sda, sector 9748 op > 0x1:(WRITE) flags 0x100000 phys_seg 1 prio class 0 > [ 103.087428] Buffer I/O error on dev sda1, logical block 1556, lost > async page write > [ 103.095309] sd 0:0:0:0: [sda] tag#0 device offline or changed > [ 103.101123] blk_update_request: I/O error, dev sda, sector 17162 op > 0x1:(WRITE) flags 0x100000 phys_seg 1 prio class 0 > [ 103.111883] Buffer I/O error on dev sda1, logical block 8970, lost > async page write I can't tell why you're getting that error. In one of my tests the device returned the same kind of error status (Sense Key = 6, ASC = 0x28) but the operation was then retried successfully. Perhaps the problem lies in the device you are testing. > >> As we need to have that working at some point, I might look into it, but > >> someone who has experience in the block layer can surely do it more > >> efficiently. > > > > I suspect that any problems you still face are caused by something else. > > > > I then formatted sda1 to ext2 (on the runtime suspend system testing > your patch) and that seems to have worked! > > Again accessing the mountpoint then yield the very same "device offline > or changed" errors. > > What kind of device are you testing? You should be easily able to > reproduce this using an "sd" device. I tested two devices: a SanDisk Cruzer USB flash drive and a g-mass-storage gadget running under dummy-hcd. They each showed up as /dev/sdb on my system. I haven't tried testing with an SD card. If you have any specific sequence of commands you would like me to run, let me know. > The problems must lie in the different other drivers we use I guess. Or the devices. Have you tried testing with a USB flash drive? Alan Stern
