On 29.01.24 10:49, David Howells wrote: > Fix netfs_unbuffered_write_iter() to return immediately if > generic_write_checks() returns 0, indicating there's nothing to write. > Note that netfs_file_write_iter() already does this. > > Also, whilst we're at it, put in checks for the size being zero before we > even take the locks. Note that generic_write_checks() can still reduce the > size to zero, so we still need that check. > > Without this, a warning similar to the following is logged to dmesg: > > netfs: Zero-sized write [R=1b6da] > > and the syscall fails with EIO, e.g.: > > /sbin/ldconfig.real: Writing of cache extension data failed: Input/output error > > This can be reproduced on 9p by: > > xfs_io -f -c 'pwrite 0 0' /xfstest.test/foo > > Fixes: 153a9961b551 ("netfs: Implement unbuffered/DIO write support") > Reported-by: Eric Van Hensbergen <ericvh@xxxxxxxxxx> > Link: https://lore.kernel.org/r/ZbQUU6QKmIftKsmo@FV7GG9FTHL/ David, thx for fixing Eric's regression, which I'm tracking. Christian, just wondering: that patch afaics is sitting in vfs.netfs for about three weeks now -- is that intentional or did it maybe fell through the cracks somehow? > [...] Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat) -- Everything you wanna know about Linux kernel regression tracking: https://linux-regtracking.leemhuis.info/about/#tldr If I did something stupid, please tell me, as explained on that page.