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
