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authorDave Chinner <dchinner@redhat.com>2013-10-29 22:11:46 +1100
committerBen Myers <bpm@sgi.com>2013-10-30 13:37:38 -0500
commit32c5483a8a13a43264809144210ec114dd70b611 (patch)
tree62db2c9a27d98cdc614dea74b3dabbe197d97bf2 /fs/xfs/xfs_mount.h
parentc963c6193a5adaec58044e238ef23516d04e5a74 (diff)
xfs: abstract the differences in dir2/dir3 via an ops vector
Lots of the dir code now goes through switches to determine what is the correct on-disk format to parse. It generally involves a "xfs_sbversion_hasfoo" check, deferencing the superblock version and feature fields and hence touching several cache lines per operation in the process. Some operations do multiple checks because they nest conditional operations and they don't pass the information in a direct fashion between each other. Hence, add an ops vector to the xfs_inode structure that is configured when the inode is initialised to point to all the correct decode and encoding operations. This will significantly reduce the branchiness and cacheline footprint of the directory object decoding and encoding. This is the first patch in a series of conversion patches. It will introduce the ops structure, the setup of it and add the first operation to the vector. Subsequent patches will convert directory ops one at a time to keep the changes simple and obvious. Just this patch shows the benefit of such an approach on code size. Just converting the two shortform dir operations as this patch does decreases the built binary size by ~1500 bytes: $ size fs/xfs/xfs.o.orig fs/xfs/xfs.o.p1 text data bss dec hex filename 794490 96802 1096 892388 d9de4 fs/xfs/xfs.o.orig 792986 96802 1096 890884 d9804 fs/xfs/xfs.o.p1 $ That's a significant decrease in the instruction cache footprint of the directory code for such a simple change, and indicates that this approach is definitely worth pursuing further. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ben Myers <bpm@sgi.com>
Diffstat (limited to 'fs/xfs/xfs_mount.h')
-rw-r--r--fs/xfs/xfs_mount.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 1fa0584b5627..973397f66c6b 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -26,6 +26,7 @@ struct xfs_mru_cache;
struct xfs_nameops;
struct xfs_ail;
struct xfs_quotainfo;
+struct xfs_dir_ops;
#ifdef HAVE_PERCPU_SB
@@ -148,6 +149,7 @@ typedef struct xfs_mount {
int m_dir_magicpct; /* 37% of the dir blocksize */
__uint8_t m_sectbb_log; /* sectlog - BBSHIFT */
const struct xfs_nameops *m_dirnameops; /* vector of dir name ops */
+ const struct xfs_dir_ops *m_dir_inode_ops; /* vector of dir inode ops */
int m_dirblksize; /* directory block sz--bytes */
int m_dirblkfsbs; /* directory block sz--fsbs */
xfs_dablk_t m_dirdatablk; /* blockno of dir data v2 */