e.g. stat reports much larger than 512 byte block size over SMB3
# stat /mnt2/foo
File: /mnt2/foo
Size: 65536 Blocks: 128 IO Block: 1048576 regular file
Device: 34h/52d Inode: 88946092640651991 Links: 1
and local file systems do the same ie "blocks" is unrelated to block size
the fs reports. Here is an example to XFS locally
# stat Makefile
File: Makefile
Size: 66247 Blocks: 136 IO Block: 4096 regular file
Device: 10302h/66306d Inode: 1076242180 Links: 1
On Fri, Mar 19, 2021 at 12:42 PM Steve French <smfrench@xxxxxxxxx> wrote:
>
> We report the block size properly (typically much larger) - but the
> kernel API returns allocation size in 512 byte units no matter what the
> block size is. Number of blocks returned for the kernel API
> inode->i_blocks
> is unrelated to the block size (simply allocation_size/512 rounded up by 1).
>
> On Fri, Mar 19, 2021 at 12:38 PM Tom Talpey <tom@xxxxxxxxxx> wrote:
> >
> > On 3/19/2021 1:25 AM, Steve French wrote:
> > > Applications that create and extend and write to a file do not
> > > expect to see 0 allocation size. When file is extended,
> > > set its allocation size to a plausible value until we have a
> > > chance to query the server for it. When the file is cached
> > > this will prevent showing an impossible number of allocated
> > > blocks (like 0). This fixes e.g. xfstests 614 which does
> > >
> > > 1) create a file and set its size to 64K
> > > 2) mmap write 64K to the file
> > > 3) stat -c %b for the file (to query the number of allocated blocks)
> > >
> > > It was failing because we returned 0 blocks. Even though we would
> > > return the correct cached file size, we returned an impossible
> > > allocation size.
> > >
> > > Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
> > > CC: <stable@xxxxxxxxxxxxxxx>
> > > ---
> > > fs/cifs/inode.c | 12 ++++++++++--
> > > 1 file changed, 10 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
> > > index 7c61bc9573c0..17a2c87b811c 100644
> > > --- a/fs/cifs/inode.c
> > > +++ b/fs/cifs/inode.c
> > > @@ -2395,7 +2395,7 @@ int cifs_getattr(struct user_namespace
> > > *mnt_userns, const struct path *path,
> > > * We need to be sure that all dirty pages are written and the server
> > > * has actual ctime, mtime and file length.
> > > */
> > > - if ((request_mask & (STATX_CTIME | STATX_MTIME | STATX_SIZE)) &&
> > > + if ((request_mask & (STATX_CTIME | STATX_MTIME | STATX_SIZE |
> > > STATX_BLOCKS)) &&
> > > !CIFS_CACHE_READ(CIFS_I(inode)) &&
> > > inode->i_mapping && inode->i_mapping->nrpages != 0) {
> > > rc = filemap_fdatawait(inode->i_mapping);
> > > @@ -2585,6 +2585,14 @@ cifs_set_file_size(struct inode *inode, struct
> > > iattr *attrs,
> > > if (rc == 0) {
> > > cifsInode->server_eof = attrs->ia_size;
> > > cifs_setsize(inode, attrs->ia_size);
> > > + /*
> > > + * i_blocks is not related to (i_size / i_blksize),
> > > + * but instead 512 byte (2**9) size is required for
> > > + * calculating num blocks. Until we can query the
> > > + * server for actual allocation size, this is best estimate
> > > + * we have for the blocks allocated for this file
> > > + */
> > > + inode->i_blocks = (512 - 1 + attrs->ia_size) >> 9;
> >
> > I don't think 512 is a very robust choice, no server uses anything
> > so small any more. MS-FSA requires the allocation quantum to be the
> > volume cluster size. Is that value available locally?
> >
> > Tom.
> >
> > > /*
> > > * The man page of truncate says if the size changed,
> > > @@ -2912,7 +2920,7 @@ cifs_setattr_nounix(struct dentry *direntry,
> > > struct iattr *attrs)
> > > sys_utimes in which case we ought to fail the call back to
> > > the user when the server rejects the call */
> > > if ((rc) && (attrs->ia_valid &
> > > - (ATTR_MODE | ATTR_GID | ATTR_UID | ATTR_SIZE)))
> > > + (ATTR_MODE | ATTR_GID | ATTR_UID | ATTR_SIZE)))
> > > rc = 0;
> > > }
> > >
>
>
>
> --
> Thanks,
>
> Steve
--
Thanks,
Steve
