When xfs is operating as the back-end of a pNFS block server, it prevents collisions between local and remote operations by requiring a lease to be held for remotely accessed blocks. Local filesystem operations break those leases before writing or mutating the extent map of the file.
A similar mechanism is needed to prevent operations on pinned dax mappings, like device-DMA, from colliding with extent unmap operations. BREAK_WRITE and BREAK_TRUNCATE are introduced as two distinct levels of layout breaking. Layouts are broken in the BREAK_WRITE case to ensure that layout-holders do not collide with local writes. Additionally, layouts are broken in the BREAK_TRUNCATE case to make sure the layout-holder has a consistent view of the file's extent map. While BREAK_WRITE breaks can be satisfied be recalling FL_LAYOUT leases, BREAK_TRUNCATE breaks additionally require waiting for busy dax-pages to go idle. Cc: "Darrick J. Wong" <[email protected]> Cc: Ross Zwisler <[email protected]> Reported-by: Dave Chinner <[email protected]> Reported-by: Christoph Hellwig <[email protected]> Signed-off-by: Dan Williams <[email protected]> --- fs/xfs/xfs_file.c | 23 +++++++++++++++++------ fs/xfs/xfs_inode.h | 18 ++++++++++++++++-- fs/xfs/xfs_ioctl.c | 2 +- fs/xfs/xfs_iops.c | 5 +++-- 4 files changed, 37 insertions(+), 11 deletions(-) diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index 5742d395a4e4..399c5221f101 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -352,7 +352,7 @@ xfs_file_aio_write_checks( xfs_ilock(ip, XFS_MMAPLOCK_EXCL); *iolock |= XFS_MMAPLOCK_EXCL; - error = xfs_break_layouts(inode, iolock); + error = xfs_break_layouts(inode, iolock, BREAK_WRITE); if (error) { *iolock &= ~XFS_MMAPLOCK_EXCL; xfs_iunlock(ip, XFS_MMAPLOCK_EXCL); @@ -762,7 +762,8 @@ xfs_file_write_iter( int xfs_break_layouts( struct inode *inode, - uint *iolock) + uint *iolock, + enum layout_break_reason reason) { struct xfs_inode *ip = XFS_I(inode); int ret; @@ -770,9 +771,19 @@ xfs_break_layouts( ASSERT(xfs_isilocked(ip, XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL)); - ret = xfs_break_leased_layouts(inode, iolock); - if (ret > 0) - ret = 0; + switch (reason) { + case BREAK_TRUNCATE: + /* fall through */ + case BREAK_WRITE: + ret = xfs_break_leased_layouts(inode, iolock); + if (ret > 0) + ret = 0; + break; + default: + ret = -EINVAL; + break; + } + return ret; } @@ -802,7 +813,7 @@ xfs_file_fallocate( return -EOPNOTSUPP; xfs_ilock(ip, iolock); - error = xfs_break_layouts(inode, &iolock); + error = xfs_break_layouts(inode, &iolock, BREAK_TRUNCATE); if (error) goto out_unlock; diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h index 74c63f3a720f..1a66c7afcf45 100644 --- a/fs/xfs/xfs_inode.h +++ b/fs/xfs/xfs_inode.h @@ -379,6 +379,20 @@ static inline void xfs_ifunlock(struct xfs_inode *ip) >> XFS_ILOCK_SHIFT) /* + * Layouts are broken in the BREAK_WRITE case to ensure that + * layout-holders do not collide with local writes. Additionally, + * layouts are broken in the BREAK_TRUNCATE case to make sure the + * layout-holder has a consistent view of the file's extent map. While + * BREAK_WRITE breaks can be satisfied be recalling FL_LAYOUT leases, + * BREAK_TRUNCATE breaks additionally require waiting for busy dax-pages + * to go idle. + */ +enum layout_break_reason { + BREAK_WRITE, + BREAK_TRUNCATE, +}; + +/* * For multiple groups support: if S_ISGID bit is set in the parent * directory, group of new file is set to that of the parent, and * new subdirectory gets S_ISGID bit from parent. @@ -447,8 +461,8 @@ int xfs_zero_eof(struct xfs_inode *ip, xfs_off_t offset, xfs_fsize_t isize, bool *did_zeroing); int xfs_zero_range(struct xfs_inode *ip, xfs_off_t pos, xfs_off_t count, bool *did_zero); -int xfs_break_layouts(struct inode *inode, uint *iolock); - +int xfs_break_layouts(struct inode *inode, uint *iolock, + enum layout_break_reason reason); /* from xfs_iops.c */ extern void xfs_setup_inode(struct xfs_inode *ip); diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c index d70a1919e787..847a67186d95 100644 --- a/fs/xfs/xfs_ioctl.c +++ b/fs/xfs/xfs_ioctl.c @@ -643,7 +643,7 @@ xfs_ioc_space( return error; xfs_ilock(ip, iolock); - error = xfs_break_layouts(inode, &iolock); + error = xfs_break_layouts(inode, &iolock, BREAK_TRUNCATE); if (error) goto out_unlock; diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c index 78eb56d447df..f9fcadb5b555 100644 --- a/fs/xfs/xfs_iops.c +++ b/fs/xfs/xfs_iops.c @@ -1026,13 +1026,14 @@ xfs_vn_setattr( int error; if (iattr->ia_valid & ATTR_SIZE) { - struct xfs_inode *ip = XFS_I(d_inode(dentry)); + struct inode *inode = d_inode(dentry); + struct xfs_inode *ip = XFS_I(inode); uint iolock; xfs_ilock(ip, XFS_MMAPLOCK_EXCL); iolock = XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL; - error = xfs_break_layouts(d_inode(dentry), &iolock); + error = xfs_break_layouts(inode, &iolock, BREAK_TRUNCATE); if (error) { xfs_iunlock(ip, XFS_MMAPLOCK_EXCL); return error;
