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[49.181.88.204]) by smtp.gmail.com with ESMTPSA id y72-20020a62644b000000b006372791d708sm24025265pfb.104.2023.05.03.14.58.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 03 May 2023 14:58:49 -0700 (PDT) Received: from dave by dread.disaster.area with local (Exim 4.92.3) (envelope-from ) id 1puKUo-00B0iy-Si; Thu, 04 May 2023 07:58:46 +1000 Date: Thu, 4 May 2023 07:58:46 +1000 From: Dave Chinner To: John Garry Cc: axboe@kernel.dk, kbusch@kernel.org, hch@lst.de, sagi@grimberg.me, martin.petersen@oracle.com, djwong@kernel.org, viro@zeniv.linux.org.uk, brauner@kernel.org, dchinner@redhat.com, jejb@linux.ibm.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, Prasad Singamsetty Subject: Re: [PATCH RFC 02/16] fs/bdev: Add atomic write support info to statx Message-ID: <20230503215846.GE3223426@dread.disaster.area> References: <20230503183821.1473305-1-john.g.garry@oracle.com> <20230503183821.1473305-3-john.g.garry@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230503183821.1473305-3-john.g.garry@oracle.com> Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On Wed, May 03, 2023 at 06:38:07PM +0000, John Garry wrote: > From: Prasad Singamsetty > > Extend statx system call to return additional info for atomic write support > support if the specified file is a block device. > > Add initial support for a block device. > > Signed-off-by: Prasad Singamsetty > Signed-off-by: John Garry > --- > block/bdev.c | 21 +++++++++++++++++++++ > fs/stat.c | 10 ++++++++++ > include/linux/blkdev.h | 4 ++++ > include/linux/stat.h | 2 ++ > include/uapi/linux/stat.h | 7 ++++++- > 5 files changed, 43 insertions(+), 1 deletion(-) > > diff --git a/block/bdev.c b/block/bdev.c > index 1795c7d4b99e..6a5fd5abaadc 100644 > --- a/block/bdev.c > +++ b/block/bdev.c > @@ -1014,3 +1014,24 @@ void bdev_statx_dioalign(struct inode *inode, struct kstat *stat) > > blkdev_put_no_open(bdev); > } > + > +/* > + * Handle statx for block devices to get properties of WRITE ATOMIC > + * feature support. > + */ > +void bdev_statx_atomic(struct inode *inode, struct kstat *stat) > +{ > + struct block_device *bdev; > + > + bdev = blkdev_get_no_open(inode->i_rdev); > + if (!bdev) > + return; > + > + stat->atomic_write_unit_min = queue_atomic_write_unit_min(bdev->bd_queue); > + stat->atomic_write_unit_max = queue_atomic_write_unit_max(bdev->bd_queue); > + stat->attributes |= STATX_ATTR_WRITE_ATOMIC; > + stat->attributes_mask |= STATX_ATTR_WRITE_ATOMIC; > + stat->result_mask |= STATX_WRITE_ATOMIC; > + > + blkdev_put_no_open(bdev); > +} > diff --git a/fs/stat.c b/fs/stat.c > index 7c238da22ef0..d20334a0e9ae 100644 > --- a/fs/stat.c > +++ b/fs/stat.c > @@ -256,6 +256,14 @@ static int vfs_statx(int dfd, struct filename *filename, int flags, > bdev_statx_dioalign(inode, stat); > } > > + /* Handle STATX_WRITE_ATOMIC for block devices */ > + if (request_mask & STATX_WRITE_ATOMIC) { > + struct inode *inode = d_backing_inode(path.dentry); > + > + if (S_ISBLK(inode->i_mode)) > + bdev_statx_atomic(inode, stat); > + } This duplicates STATX_DIOALIGN bdev handling. Really, the bdev attribute handling should be completely factored out of vfs_statx() - blockdevs are not the common fastpath for stat operations. Somthing like: /* * If this is a block device inode, override the filesystem * attributes with the block device specific parameters * that need to be obtained from the bdev backing inode. */ if (S_ISBLK(d_backing_inode(path.dentry)->i_mode)) bdev_statx(path.dentry, stat); And then all the overrides can go in the one function that doesn't need to repeatedly check S_ISBLK().... > diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h > index 6b6f2992338c..19d33b2897b2 100644 > --- a/include/linux/blkdev.h > +++ b/include/linux/blkdev.h > @@ -1527,6 +1527,7 @@ int sync_blockdev_range(struct block_device *bdev, loff_t lstart, loff_t lend); > int sync_blockdev_nowait(struct block_device *bdev); > void sync_bdevs(bool wait); > void bdev_statx_dioalign(struct inode *inode, struct kstat *stat); > +void bdev_statx_atomic(struct inode *inode, struct kstat *stat); > void printk_all_partitions(void); > #else > static inline void invalidate_bdev(struct block_device *bdev) > @@ -1546,6 +1547,9 @@ static inline void sync_bdevs(bool wait) > static inline void bdev_statx_dioalign(struct inode *inode, struct kstat *stat) > { > } > +static inline void bdev_statx_atomic(struct inode *inode, struct kstat *stat) > +{ > +} > static inline void printk_all_partitions(void) > { > } That also gets rid of the need for all these fine grained exports out of the bdev code for statx.... > diff --git a/include/linux/stat.h b/include/linux/stat.h > index 52150570d37a..dfa69ecfaacf 100644 > --- a/include/linux/stat.h > +++ b/include/linux/stat.h > @@ -53,6 +53,8 @@ struct kstat { > u32 dio_mem_align; > u32 dio_offset_align; > u64 change_cookie; > + u32 atomic_write_unit_max; > + u32 atomic_write_unit_min; > }; > > /* These definitions are internal to the kernel for now. Mainly used by nfsd. */ > diff --git a/include/uapi/linux/stat.h b/include/uapi/linux/stat.h > index 7cab2c65d3d7..c99d7cac2aa6 100644 > --- a/include/uapi/linux/stat.h > +++ b/include/uapi/linux/stat.h > @@ -127,7 +127,10 @@ struct statx { > __u32 stx_dio_mem_align; /* Memory buffer alignment for direct I/O */ > __u32 stx_dio_offset_align; /* File offset alignment for direct I/O */ > /* 0xa0 */ > - __u64 __spare3[12]; /* Spare space for future expansion */ > + __u32 stx_atomic_write_unit_max; > + __u32 stx_atomic_write_unit_min; > + /* 0xb0 */ > + __u64 __spare3[11]; /* Spare space for future expansion */ > /* 0x100 */ > }; No documentation on what units these are in. Is there a statx() man page update for this addition? Cheers, Dave. -- Dave Chinner david@fromorbit.com