Hi Oliver, On Thu, 28 Apr 2016 19:42:21 +0200, Oliver Rath wrote : > is it possible, to "decache" a fileio-device without destroying it? > > I have an (deactivated) cached fileio-device here: > > # cat info > Status: DEACTIVATED Max Queue Depth: 0 SectorSize: 0 HwMaxSectors: > 0 TCM FILEIO ID: 0 File: /dev/dm-8 Size: 5368709120 Mode: > Buffered-WCE > > but flushing the buffer (or just deactivating) doesnt work: > > # echo "fd_buffered_io=0" > control > bash: echo: write error: Invalid argument > > And dmesg tells me: > > [101828.839116] bogus fd_buffered_io=0 value > > > Is it not possible to deactivate buffer without destroying the fileio? I think the proper way to disable the write cache is to set the emulate_write_cache attribute of your fileio backstore to 0: With `targetcli`: /backstores/fileio/file1> set attribute emulate_write_cache=0 Parameter emulate_write_cache is now '0'. Or from the shell in configfs: $ sudo sh -c 'echo 0 > attrib/emulate_write_cache' > The other direction seems to work: > > # echo > "fd_dev_path=/dev/dm-9,fd_dev_name=/dev/dm-9,fd_dev_size=$(blockdev > --getsize64 /dev/dm-9)" > control > # cat info > Status: DEACTIVATED Max Queue Depth: 0 SectorSize: 0 HwMaxSectors: > 0 TCM FILEIO ID: 0 File: /dev/dm-9 Size: 7516192768 Mode: > O_DSYNC > > # echo "fd_buffered_io=1" > control > # cat info > Status: DEACTIVATED Max Queue Depth: 0 SectorSize: 0 HwMaxSectors: > 0 TCM FILEIO ID: 0 File: /dev/dm-9 Size: 7516192768 Mode: > Buffered-WCE Looking at the code, it seems that "fd_buffered_io", if specified, must be set to 1. Other values are not accepted. http://lxr.free-electrons.com/source/drivers/target/target_core_file.c#L661 Hope that helps, -- Christophe Vu-Brugier -- To unsubscribe from this list: send the line "unsubscribe target-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
