similar to: [PATCH v2] file: Normalize errno value for ENODEV

Fix issues Eric found in the original patch: https://www.redhat.com/archives/libguestfs/2018-July/msg00072.html - When handling ENODEV, the caller is expecting ENOTSUPP to trigger fallback. - ENODEV should be ignored in file_trim. Tested only on Fedora 28. --- plugins/file/file.c | 33 ++++++++++++++++++++++++--------- 1 file changed, 24 insertions(+), 9 deletions(-) diff --git

When using block device on RHEL 7.5, file plugin fails to zero with this error (copied from strace): [pid 39551] fallocate(8, FALLOC_FL_ZERO_RANGE, 1536, 64000) = -1 ENODEV (No such device) This is expected error according to the manual: ENODEV fd does not refer to a regular file or a directory. (If fd is a pipe or FIFO, a different error results.) Treat this error as EOPNOSUPP. Tested only

On Fri, Jul 27, 2018 at 04:23:10PM -0500, Eric Blake wrote: > On 07/27/2018 04:03 PM, Nir Soffer wrote: > >When using block device on RHEL 7.5, file plugin fails to zero with this > >error (copied from strace): > > > >[pid 39551] fallocate(8, FALLOC_FL_ZERO_RANGE, 1536, 64000) = -1 ENODEV (No such device) > > > >This is expected error according to the manual:

This is the second version to support efficient zero for block devices on older kernels (e.g. RHEL 7.5), and file systems that do not support yet FALLOC_FS_ZERO_RANGE (e.g. NFS 4.2). Changes since v1: - Split to smaller patches - Skip linux only includes on other systems - Skip code using BLKZEROOUT if the macro is not defined - Try BLKZEROOUT only if the offset and count are aligned to device

On Mon, Jul 30, 2018 at 9:23 PM Eric Blake <eblake@redhat.com> wrote: > On 07/30/2018 12:02 PM, Nir Soffer wrote: > > Fix issues Eric found in the original patch: > > https://www.redhat.com/archives/libguestfs/2018-July/msg00072.html > > > > - When handling ENODEV, the caller is expecting EOPNOTSUPP to trigger > > fallback. > > - ENODEV should be

If we may not trim, we tried ZERO_RANGE, but this is not well supported yet, for example it is not available on NFS 4.2. ZERO_RANGE and PUNCH_HOLE are supported now on block devices, but not on RHRL 7, so we fallback to slow manual zeroing there. Change the logic to support block devices on RHEL 7, and file systems that do not support ZERO_RANGE. The new logic: - If we may trim, try PUNCH_HOLE -

This is the third version to support efficient zero for block devices on older kernels (e.g. RHEL 7.5), and file systems that do not support yet FALLOC_FS_ZERO_RANGE (e.g. NFS 4.2). Changes since v2: - Revert file_can_trim change, since it is too late to change the value after negotiation. Changing the capability dinamically may be useful internally, but it should be done via other means. -

On 08/02/2018 02:05 PM, Nir Soffer wrote: > When using file systems not supporting ZERO_RANGE (e.g. NFS 4.2) or > block device on kernel < 4.9, we used to call fallocate() for every > zero, fail with EOPNOTSUPP, and fallback to manual zeroing. When > trimming, we used to try unsupported fallocate() on every call. > > Change file handle to remember if punching holes or

This version addresses some of the comments on v2. Changes since v2: - file_zero: Add missing space in function call - is_aligned: Assert that align is indeed a power of 2 - Spelling in commit message Not changed: - Eric commented that spacing was off: https://www.redhat.com/archives/libguestfs/2018-August/msg00113.html but I could not find anything wrong. - Eric asked if ioctl.h will cause

When using file systems not supporting ZERO_RANGE (e.g. NFS 4.2) or block device on kernel < 4.9, we used to call fallocate() for every zero, fail with EOPNOTSUPP, and fallback to manual zeroing. When trimming, we used to try unsupported fallocate() on every call. Change file handle to remember if punching holes or zeroing range are supported, and avoid unsupported calls. - zero changed to:

When using file systems not supporting ZERO_RANGE (e.g. NFS 4.2) or block device on kernel < 4.9, we used to call fallocate() for every zero, fail with EOPNOTSUPP, and fallback to manual zeroing. When trimming, we used to try unsupported fallocate() on every call. Change file handle to remember if punching holes or zeroing range are supported, and avoid unsupported calls. - zero changed to:

When using file systems not supporting ZERO_RANGE (e.g. NFS 4.2) or block device on kernel < 4.9, we used to call fallocate() for every zero, fail with EOPNOTSUPP, and fallback to manual zeroing. When trimming, we used to try unsupported fallocate() on every call. Change file handle to remember if punching holes or zeroing range are supported, and avoid unsupported calls. - zero changed to:

This version addresses comments on v3. Changes since v3: - Finally got spacing right (Eric) - Reorder includes (Richard) - Return 0 or -1 instead of r (Richard) - Add common/include/isaligned.h to Makefile.am (Richard) v3 was here: https://www.redhat.com/archives/libguestfs/2018-August/msg00177.html Nir Soffer (4): file: Avoid unsupported fallocate() calls file: Support zero without

When using file systems not supporting ZERO_RANGE (e.g. NFS 4.2) or block device on kernel < 4.9, we used to call fallocate() for every zero, fail with EOPNOTSUPP, and fallback to manual zeroing. When trimming, we used to try unsupported fallocate() on every call. Change file handle to remember if punching holes or zeroing range are supported, and avoid unsupported calls. - can_trim changed

There's a lot of code in nbdkit-file-plugin which it would be nice to reuse elsewhere. One possible approach (as outlined here) is simply to move the file callbacks (like file.pread, file.pwrite, file.zero etc) to a new mini-library. They can then be consumed by other plugins fairly easily by doing: static void * foo_open (int readonly) { struct fileops *fops; int fd, flags; /*

Needs some work still, see in particular the commit message for patch 3. Rich.

Writing "file-like" plugins is hard because you have to implement your own .zero, .trim, .extents, etc, and that is very complicated. However implementations of these functions already exist in the file plugin. By factoring out the file plugin into a separate "fileops" mini-library we can reuse these implementations in other plugins. This refactoring commit creates a new

We already have support in the file driver for punching holes during .zero with the may_trim flag (via FALLOC_FL_PUNCH_HOLE), so we should use the same mechanism to support .trim. Note that the NBD spec says that trim is advisory (we can return success even if we did nothing); but at the same time, it's nicer to avoid advertising the feature if we know for sure we can't do it, so we also

If we may not trim, we tried ZERO_RANGE, but this is not well supported yet, for example it is not available on NFS 4.2. ZERO_RANGE and PUNCH_HOLE are supported now on block devices, but not on RHRL 7, so we fallback to slow manual zeroing there. Change the logic to support block devices on RHEL 7, and file systems that do not support ZERO_RANGE. The new logic: - If we may trim, try PUNCH_HOLE -

On 07/28/2018 06:42 AM, Nir Soffer wrote: > Fix issues Eric found in the original patch: > https://www.redhat.com/archives/libguestfs/2018-July/msg00072.html > > - When handling ENODEV, the caller is expecting ENOTSUPP to trigger > fallback. > - ENODEV should be ignored in file_trim. > > Tested only on Fedora 28. > --- > plugins/file/file.c | 33