From: "Darrick J. Wong" <darrick.wong@oracle.com> To: ira.weiny@intel.com Cc: linux-kernel@vger.kernel.org, Alexander Viro <viro@zeniv.linux.org.uk>, Dan Williams <dan.j.williams@intel.com>, Dave Chinner <david@fromorbit.com>, Christoph Hellwig <hch@lst.de>, "Theodore Y. Ts'o" <tytso@mit.edu>, Jan Kara <jack@suse.cz>, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [RFC PATCH V2 08/12] fs/xfs: Add lock/unlock mode to xfs Date: Mon, 13 Jan 2020 14:19:57 -0800 Message-ID: <20200113221957.GN8247@magnolia> (raw) In-Reply-To: <20200110192942.25021-9-ira.weiny@intel.com> On Fri, Jan 10, 2020 at 11:29:38AM -0800, ira.weiny@intel.com wrote: > From: Ira Weiny <ira.weiny@intel.com> > > XFS requires regular files to be locked while changing to/from DAX mode. > > Define a new DAX lock type and implement the [un]lock_mode() inode > operation callbacks. > > We define a new XFS_DAX_* lock type to carry the lock through the > transaction because we don't want to use IOLOCK as that would cause > performance issues with locking of the inode itself. > > Signed-off-by: Ira Weiny <ira.weiny@intel.com> > --- > fs/xfs/xfs_icache.c | 2 ++ > fs/xfs/xfs_inode.c | 37 +++++++++++++++++++++++++++++++++++-- > fs/xfs/xfs_inode.h | 12 ++++++++++-- > fs/xfs/xfs_iops.c | 24 +++++++++++++++++++++++- > 4 files changed, 70 insertions(+), 5 deletions(-) > > diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c > index 8dc2e5414276..0288672e8902 100644 > --- a/fs/xfs/xfs_icache.c > +++ b/fs/xfs/xfs_icache.c > @@ -74,6 +74,8 @@ xfs_inode_alloc( > INIT_LIST_HEAD(&ip->i_ioend_list); > spin_lock_init(&ip->i_ioend_lock); > > + percpu_init_rwsem(&ip->i_dax_sem); > + > return ip; > } > > diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c > index 401da197f012..e8fd95b75e5b 100644 > --- a/fs/xfs/xfs_inode.c > +++ b/fs/xfs/xfs_inode.c > @@ -142,12 +142,12 @@ xfs_ilock_attr_map_shared( > * > * Basic locking order: > * > - * i_rwsem -> i_mmap_lock -> page_lock -> i_ilock > + * i_rwsem -> i_dax_sem -> i_mmap_lock -> page_lock -> i_ilock Mmmmmm, more locks. Can we skip the extra lock if CONFIG_FSDAX=n or if the filesystem devices don't support DAX at all? Also, I don't think we're actually following the i_rwsem -> i_daxsem order in fallocate, and possibly elsewhere too? Does the vfs have to take the i_dax_sem to do remapping things like reflink? (Pretend that reflink and dax are compatible for the moment) > * mmap_sem locking order: > * > * i_rwsem -> page lock -> mmap_sem > - * mmap_sem -> i_mmap_lock -> page_lock > + * mmap_sem -> i_dax_sem -> i_mmap_lock -> page_lock > * > * The difference in mmap_sem locking order mean that we cannot hold the > * i_mmap_lock over syscall based read(2)/write(2) based IO. These IO paths can > @@ -181,6 +181,13 @@ xfs_ilock( > ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) != > (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)); > ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_SUBCLASS_MASK)) == 0); > + ASSERT((lock_flags & (XFS_DAX_SHARED | XFS_DAX_EXCL)) != > + (XFS_DAX_SHARED | XFS_DAX_EXCL)); > + > + if (lock_flags & XFS_DAX_EXCL) > + percpu_down_write(&ip->i_dax_sem); > + else if (lock_flags & XFS_DAX_SHARED) > + percpu_down_read(&ip->i_dax_sem); > > if (lock_flags & XFS_IOLOCK_EXCL) { > down_write_nested(&VFS_I(ip)->i_rwsem, > @@ -224,6 +231,8 @@ xfs_ilock_nowait( > * You can't set both SHARED and EXCL for the same lock, > * and only XFS_IOLOCK_SHARED, XFS_IOLOCK_EXCL, XFS_ILOCK_SHARED, > * and XFS_ILOCK_EXCL are valid values to set in lock_flags. > + * > + * XFS_DAX_* is not allowed > */ > ASSERT((lock_flags & (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)) != > (XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)); > @@ -232,6 +241,7 @@ xfs_ilock_nowait( > ASSERT((lock_flags & (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)) != > (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)); > ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_SUBCLASS_MASK)) == 0); > + ASSERT((lock_flags & (XFS_DAX_SHARED | XFS_DAX_EXCL)) == 0); > > if (lock_flags & XFS_IOLOCK_EXCL) { > if (!down_write_trylock(&VFS_I(ip)->i_rwsem)) > @@ -302,6 +312,8 @@ xfs_iunlock( > (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)); > ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_SUBCLASS_MASK)) == 0); > ASSERT(lock_flags != 0); > + ASSERT((lock_flags & (XFS_DAX_SHARED | XFS_DAX_EXCL)) != > + (XFS_DAX_SHARED | XFS_DAX_EXCL)); > > if (lock_flags & XFS_IOLOCK_EXCL) > up_write(&VFS_I(ip)->i_rwsem); > @@ -318,6 +330,11 @@ xfs_iunlock( > else if (lock_flags & XFS_ILOCK_SHARED) > mrunlock_shared(&ip->i_lock); > > + if (lock_flags & XFS_DAX_EXCL) > + percpu_up_write(&ip->i_dax_sem); > + else if (lock_flags & XFS_DAX_SHARED) > + percpu_up_read(&ip->i_dax_sem); > + > trace_xfs_iunlock(ip, lock_flags, _RET_IP_); > } > > @@ -333,6 +350,8 @@ xfs_ilock_demote( > ASSERT(lock_flags & (XFS_IOLOCK_EXCL|XFS_MMAPLOCK_EXCL|XFS_ILOCK_EXCL)); > ASSERT((lock_flags & > ~(XFS_IOLOCK_EXCL|XFS_MMAPLOCK_EXCL|XFS_ILOCK_EXCL)) == 0); > + /* XFS_DAX_* is not allowed */ > + ASSERT((lock_flags & (XFS_DAX_SHARED | XFS_DAX_EXCL)) == 0); > > if (lock_flags & XFS_ILOCK_EXCL) > mrdemote(&ip->i_lock); > @@ -369,6 +388,13 @@ xfs_isilocked( > return rwsem_is_locked(&VFS_I(ip)->i_rwsem); > } > > + if (lock_flags & (XFS_DAX_EXCL|XFS_DAX_SHARED)) { > + if (!(lock_flags & XFS_DAX_SHARED)) > + return !debug_locks || > + percpu_rwsem_is_held(&ip->i_dax_sem, 0); > + return rwsem_is_locked(&ip->i_dax_sem); > + } > + > ASSERT(0); > return 0; > } > @@ -465,6 +491,9 @@ xfs_lock_inodes( > ASSERT(!(lock_mode & XFS_ILOCK_EXCL) || > inodes <= XFS_ILOCK_MAX_SUBCLASS + 1); > > + /* XFS_DAX_* is not allowed */ > + ASSERT((lock_mode & (XFS_DAX_SHARED | XFS_DAX_EXCL)) == 0); > + > if (lock_mode & XFS_IOLOCK_EXCL) { > ASSERT(!(lock_mode & (XFS_MMAPLOCK_EXCL | XFS_ILOCK_EXCL))); > } else if (lock_mode & XFS_MMAPLOCK_EXCL) > @@ -566,6 +595,10 @@ xfs_lock_two_inodes( > ASSERT(!(ip0_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)) || > !(ip1_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL))); > > + /* XFS_DAX_* is not allowed */ > + ASSERT((ip0_mode & (XFS_DAX_SHARED | XFS_DAX_EXCL)) == 0); > + ASSERT((ip1_mode & (XFS_DAX_SHARED | XFS_DAX_EXCL)) == 0); > + > ASSERT(ip0->i_ino != ip1->i_ino); > > if (ip0->i_ino > ip1->i_ino) { > diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h > index 492e53992fa9..693ca66bd89b 100644 > --- a/fs/xfs/xfs_inode.h > +++ b/fs/xfs/xfs_inode.h > @@ -67,6 +67,9 @@ typedef struct xfs_inode { > spinlock_t i_ioend_lock; > struct work_struct i_ioend_work; > struct list_head i_ioend_list; > + > + /* protect changing the mode to/from DAX */ > + struct percpu_rw_semaphore i_dax_sem; > } xfs_inode_t; > > /* Convert from vfs inode to xfs inode */ > @@ -278,10 +281,13 @@ static inline void xfs_ifunlock(struct xfs_inode *ip) > #define XFS_ILOCK_SHARED (1<<3) > #define XFS_MMAPLOCK_EXCL (1<<4) > #define XFS_MMAPLOCK_SHARED (1<<5) > +#define XFS_DAX_EXCL (1<<6) > +#define XFS_DAX_SHARED (1<<7) > > #define XFS_LOCK_MASK (XFS_IOLOCK_EXCL | XFS_IOLOCK_SHARED \ > | XFS_ILOCK_EXCL | XFS_ILOCK_SHARED \ > - | XFS_MMAPLOCK_EXCL | XFS_MMAPLOCK_SHARED) > + | XFS_MMAPLOCK_EXCL | XFS_MMAPLOCK_SHARED \ > + | XFS_DAX_EXCL | XFS_DAX_SHARED) > > #define XFS_LOCK_FLAGS \ > { XFS_IOLOCK_EXCL, "IOLOCK_EXCL" }, \ > @@ -289,7 +295,9 @@ static inline void xfs_ifunlock(struct xfs_inode *ip) > { XFS_ILOCK_EXCL, "ILOCK_EXCL" }, \ > { XFS_ILOCK_SHARED, "ILOCK_SHARED" }, \ > { XFS_MMAPLOCK_EXCL, "MMAPLOCK_EXCL" }, \ > - { XFS_MMAPLOCK_SHARED, "MMAPLOCK_SHARED" } > + { XFS_MMAPLOCK_SHARED, "MMAPLOCK_SHARED" }, \ > + { XFS_DAX_EXCL, "DAX_EXCL" }, \ Whitespace between the comma & string. > + { XFS_DAX_SHARED, "DAX_SHARED" } > > > /* > diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c > index d6843cdb51d0..a2f2604c3187 100644 > --- a/fs/xfs/xfs_iops.c > +++ b/fs/xfs/xfs_iops.c > @@ -1158,6 +1158,16 @@ xfs_vn_tmpfile( > return xfs_generic_create(dir, dentry, mode, 0, true); > } > > +static void xfs_lock_mode(struct inode *inode) > +{ > + xfs_ilock(XFS_I(inode), XFS_DAX_SHARED); > +} > + > +static void xfs_unlock_mode(struct inode *inode) > +{ > + xfs_iunlock(XFS_I(inode), XFS_DAX_SHARED); > +} > + > static const struct inode_operations xfs_inode_operations = { > .get_acl = xfs_get_acl, > .set_acl = xfs_set_acl, > @@ -1168,6 +1178,18 @@ static const struct inode_operations xfs_inode_operations = { > .update_time = xfs_vn_update_time, > }; > > +static const struct inode_operations xfs_reg_inode_operations = { > + .get_acl = xfs_get_acl, > + .set_acl = xfs_set_acl, > + .getattr = xfs_vn_getattr, > + .setattr = xfs_vn_setattr, > + .listxattr = xfs_vn_listxattr, > + .fiemap = xfs_vn_fiemap, > + .update_time = xfs_vn_update_time, > + .lock_mode = xfs_lock_mode, > + .unlock_mode = xfs_unlock_mode, > +}; > + > static const struct inode_operations xfs_dir_inode_operations = { > .create = xfs_vn_create, > .lookup = xfs_vn_lookup, > @@ -1372,7 +1394,7 @@ xfs_setup_iops( > > switch (inode->i_mode & S_IFMT) { > case S_IFREG: > - inode->i_op = &xfs_inode_operations; > + inode->i_op = &xfs_reg_inode_operations; xfs_file_inode_operations? --D > inode->i_fop = &xfs_file_operations; > if (IS_DAX(inode)) > inode->i_mapping->a_ops = &xfs_dax_aops; > -- > 2.21.0 >
next prev parent reply index Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-01-10 19:29 [RFC PATCH V2 00/12] Enable per-file/directory DAX operations V2 ira.weiny 2020-01-10 19:29 ` [RFC PATCH V2 01/12] fs/stat: Define DAX statx attribute ira.weiny 2020-01-15 11:37 ` Jan Kara 2020-01-15 17:38 ` Darrick J. Wong 2020-01-15 19:45 ` Ira Weiny 2020-01-15 20:10 ` Dan Williams 2020-01-15 22:38 ` Ira Weiny 2020-01-16 5:39 ` Darrick J. Wong 2020-01-16 6:05 ` Dan Williams 2020-01-16 6:18 ` Darrick J. Wong 2020-01-16 6:25 ` Dan Williams 2020-01-18 9:11 ` Dave Chinner 2020-01-16 17:55 ` Ira Weiny 2020-01-16 18:04 ` Darrick J. Wong 2020-01-16 18:52 ` Ira Weiny 2020-01-16 22:19 ` Darrick J. Wong 2020-01-17 11:58 ` Jan Kara 2020-01-10 19:29 ` [RFC PATCH V2 02/12] fs/xfs: Isolate the physical DAX flag from effective ira.weiny 2020-01-10 19:29 ` [RFC PATCH V2 03/12] fs/xfs: Separate functionality of xfs_inode_supports_dax() ira.weiny 2020-01-10 19:29 ` [RFC PATCH V2 04/12] fs/xfs: Clean up DAX support check ira.weiny 2020-01-10 19:29 ` [RFC PATCH V2 05/12] fs: remove unneeded IS_DAX() check ira.weiny 2020-01-16 9:38 ` Jan Kara 2020-01-16 18:47 ` Ira Weiny 2020-01-10 19:29 ` [RFC PATCH V2 06/12] fs/xfs: Check if the inode supports DAX under lock ira.weiny 2020-01-10 19:29 ` [RFC PATCH V2 07/12] fs: Add locking for a dynamic inode 'mode' ira.weiny 2020-01-13 22:12 ` Darrick J. Wong 2020-01-14 0:20 ` Ira Weiny 2020-01-14 1:03 ` Darrick J. Wong 2020-01-15 19:08 ` Ira Weiny 2020-01-16 5:40 ` Darrick J. Wong 2020-01-16 18:54 ` Ira Weiny 2020-01-10 19:29 ` [RFC PATCH V2 08/12] fs/xfs: Add lock/unlock mode to xfs ira.weiny 2020-01-13 22:19 ` Darrick J. Wong [this message] 2020-01-14 0:35 ` Ira Weiny 2020-01-15 0:57 ` Ira Weiny 2020-01-15 23:52 ` Ira Weiny 2020-01-16 9:24 ` Jan Kara 2020-01-16 19:12 ` Ira Weiny 2020-01-10 19:29 ` [RFC PATCH V2 09/12] fs: Prevent mode change if file is mmap'ed ira.weiny 2020-01-13 22:22 ` Darrick J. Wong 2020-01-14 0:46 ` Ira Weiny 2020-01-14 1:30 ` Darrick J. Wong 2020-01-14 17:53 ` Ira Weiny 2020-01-15 11:34 ` Jan Kara 2020-01-15 18:24 ` Ira Weiny 2020-01-15 10:21 ` David Laight 2020-01-15 17:53 ` Ira Weiny 2020-01-10 19:29 ` [RFC PATCH V2 10/12] fs/xfs: Fix truncate up ira.weiny 2020-01-13 22:27 ` Darrick J. Wong 2020-01-14 0:40 ` Ira Weiny 2020-01-14 1:14 ` Darrick J. Wong 2020-01-14 19:00 ` Ira Weiny 2020-01-14 19:39 ` Ira Weiny 2020-01-10 19:29 ` [RFC PATCH V2 11/12] fs/xfs: Clean up locking in dax invalidate ira.weiny 2020-01-10 19:29 ` [RFC PATCH V2 12/12] fs/xfs: Allow toggle of effective DAX flag ira.weiny
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