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xfs: set a default CoW extent size of 32 blocks 

If the admin doesn't set a CoW extent size or a regular extent size
hint, default to creating CoW reservations 32 blocks long to reduce
fragmentation.

Signed-off-by: DarricK J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Darrick J. Wong 2016-10-03 09:11:49 -07:00
parent 3f165b334e
commit e153aa7990
2 changed files with 9 additions and 4 deletions
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8
fs/xfs/xfs_inode.c
View File

@ -80,7 +80,8 @@ xfs_get_extsz_hint(
/*
* Helper function to extract CoW extent size hint from inode.
* Between the extent size hint and the CoW extent size hint, we
* return the greater of the two.
* return the greater of the two. If the value is zero (automatic),
* use the default size.
*/
xfs_extlen_t
xfs_get_cowextsz_hint(
@ -93,9 +94,10 @@ xfs_get_cowextsz_hint(
a = ip->i_d.di_cowextsize;
b = xfs_get_extsz_hint(ip);
if (a > b)
a = max(a, b);
if (a == 0)
return XFS_DEFAULT_COWEXTSZ_HINT;
return a;
return b;
}
/*

3
fs/xfs/xfs_inode.h
View File

@ -490,4 +490,7 @@ do { \
extern struct kmem_zone *xfs_inode_zone;
/* The default CoW extent size hint. */
#define XFS_DEFAULT_COWEXTSZ_HINT 32
#endif /* __XFS_INODE_H__ */