xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

xfs: prepare xfs_break_layouts() for another layout type

Browse Source 
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_UNMAP 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_UNMAP 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_UNMAP breaks additionally require
waiting for busy dax-pages to go idle while holding XFS_MMAPLOCK_EXCL.

After this refactoring xfs_break_layouts() becomes the entry point for
coordinating both types of breaks. Finally, xfs_break_leased_layouts()
becomes just the BREAK_WRITE handler.

Note that the unlock tracking is needed in a follow on change. That will
coordinate retrying either break handler until both successfully test
for a lease break while maintaining the lock state.

Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
Reported-by: Dave Chinner <david@fromorbit.com>
Reported-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams
2018-03-20 14:42:38 -07:00
parent c63a8eae63
commit 69eb5fa10e
6 changed files with 53 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
fs/xfs/xfs_inode.h
View File

@@ -378,6 +378,20 @@ static inline void xfs_ifunlock(struct xfs_inode *ip)
#define XFS_ILOCK_DEP(flags) (((flags) & XFS_ILOCK_DEP_MASK) \
>> 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_UNMAP case to make sure the
* layout-holder has a consistent view of the file's extent map. While
* BREAK_WRITE breaks can be satisfied by recalling FL_LAYOUT leases,
* BREAK_UNMAP breaks additionally require waiting for busy dax-pages to
* go idle.
*/
enum layout_break_reason {
BREAK_WRITE,
BREAK_UNMAP,
};
/*
* 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
@@ -443,6 +457,8 @@ enum xfs_prealloc_flags {
int xfs_update_prealloc_flags(struct xfs_inode *ip,
enum xfs_prealloc_flags flags);
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);