[XFS] 929045 567344 This mod introduces multi-level in-core file extent

functionality, building upon the new layout introduced in mod
xfs-linux:xfs-kern:207390a.  The new multi-level extent allocations are
only required for heavily fragmented files, so the old-style linear extent
list is used on files until the extents reach a pre-determined size of 4k.
4k buffers are used because this is the system page size on Linux i386 and
systems with larger page sizes don't seem to gain much, if anything, by
using their native page size as the extent buffer size. Also, using 4k
extent buffers everywhere provides a consistent interface for CXFS across
different platforms.  The 4k extent buffers are managed by an indirection
array (xfs_ext_irec_t) which is basically just a pointer array with a bit
of extra information to keep track of the number of extents in each buffer
as well as the extent offset of each buffer.  Major changes include:  -
Add multi-level in-core file extent functionality to the xfs_iext_  
subroutines introduced in mod:	xfs-linux:xfs-kern:207390a  - Introduce 13
new subroutines which add functionality for multi-level   in-core file
extents:	 xfs_iext_add_indirect_multi()	      
xfs_iext_remove_indirect()	   xfs_iext_realloc_indirect()	      
xfs_iext_indirect_to_direct()	      xfs_iext_bno_to_irec()	    
xfs_iext_idx_to_irec()	       xfs_iext_irec_init()	   
xfs_iext_irec_new()	    xfs_iext_irec_remove()	  
xfs_iext_irec_compact() 	xfs_iext_irec_compact_pages()	     
xfs_iext_irec_compact_full()	     xfs_iext_irec_update_extoffs()

SGI-PV: 928864
SGI-Modid: xfs-linux-melb:xfs-kern:207393a

Signed-off-by: Mandy Kirkconnell <alkirkco@sgi.com>
Signed-off-by: Nathan Scott <nathans@sgi.com>

1 files changed, 47 insertions, 5 deletions

diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index 740b73fabd2f..3c1df1d642fa 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -25,10 +25,37 @@
 #define XFS_ATTR_FORK   1
 
 /*
+ * The following xfs_ext_irec_t struct introduces a second (top) level
+ * to the in-core extent allocation scheme. These structs are allocated
+ * in a contiguous block, creating an indirection array where each entry
+ * (irec) contains a pointer to a buffer of in-core extent records which
+ * it manages. Each extent buffer is 4k in size, since 4k is the system
+ * page size on Linux i386 and systems with larger page sizes don't seem
+ * to gain much, if anything, by using their native page size as the
+ * extent buffer size. Also, using 4k extent buffers everywhere provides
+ * a consistent interface for CXFS across different platforms.
+ *
+ * There is currently no limit on the number of irec's (extent lists)
+ * allowed, so heavily fragmented files may require an indirection array
+ * which spans multiple system pages of memory. The number of extents
+ * which would require this amount of contiguous memory is very large
+ * and should not cause problems in the foreseeable future. However,
+ * if the memory needed for the contiguous array ever becomes a problem,
+ * it is possible that a third level of indirection may be required.
+ */
+typedef struct xfs_ext_irec {
+        xfs_bmbt_rec_t  *er_extbuf;     /* block of extent records */
+        xfs_extnum_t    er_extoff;      /* extent offset in file */
+        xfs_extnum_t    er_extcount;    /* number of extents in page/block */
+} xfs_ext_irec_t;
+
+/*
  * File incore extent information, present for each of data & attr forks.
  */
-#define XFS_INLINE_EXTS 2
-#define XFS_INLINE_DATA 32
+#define XFS_IEXT_BUFSZ          4096
+#define XFS_LINEAR_EXTS         (XFS_IEXT_BUFSZ / (uint)sizeof(xfs_bmbt_rec_t))
+#define XFS_INLINE_EXTS         2
+#define XFS_INLINE_DATA         32
 typedef struct xfs_ifork {
         int                     if_bytes;       /* bytes in if_u1 */
         int                     if_real_bytes;  /* bytes allocated in if_u1 */
@@ -39,6 +66,7 @@ typedef struct xfs_ifork {
         xfs_extnum_t            if_lastex;      /* last if_extents used */
         union {
                 xfs_bmbt_rec_t  *if_extents;    /* linear map file exts */
+                xfs_ext_irec_t  *if_ext_irec;   /* irec map file exts */
                 char            *if_data;       /* inline file data */
         } if_u1;
         union {
@@ -61,9 +89,10 @@ typedef struct xfs_ifork {
 /*
  * Per-fork incore inode flags.
  */
-#define XFS_IFINLINE    0x0001  /* Inline data is read in */
-#define XFS_IFEXTENTS   0x0002  /* All extent pointers are read in */
-#define XFS_IFBROOT     0x0004  /* i_broot points to the bmap b-tree root */
+#define XFS_IFINLINE    0x01    /* Inline data is read in */
+#define XFS_IFEXTENTS   0x02    /* All extent pointers are read in */
+#define XFS_IFBROOT     0x04    /* i_broot points to the bmap b-tree root */
+#define XFS_IFEXTIREC   0x08    /* Indirection array of extent blocks */
 
 /*
  * Flags for xfs_imap() and xfs_dilocate().
@@ -438,13 +467,26 @@ xfs_bmbt_rec_t	*xfs_iext_get_ext(xfs_ifork_t *, xfs_extnum_t);
 void            xfs_iext_insert(xfs_ifork_t *, xfs_extnum_t, xfs_extnum_t,
                                 xfs_bmbt_irec_t *);
 void            xfs_iext_add(xfs_ifork_t *, xfs_extnum_t, int);
+void            xfs_iext_add_indirect_multi(xfs_ifork_t *, int, xfs_extnum_t, int);
 void            xfs_iext_remove(xfs_ifork_t *, xfs_extnum_t, int);
 void            xfs_iext_remove_inline(xfs_ifork_t *, xfs_extnum_t, int);
 void            xfs_iext_remove_direct(xfs_ifork_t *, xfs_extnum_t, int);
+void            xfs_iext_remove_indirect(xfs_ifork_t *, xfs_extnum_t, int);
 void            xfs_iext_realloc_direct(xfs_ifork_t *, int);
+void            xfs_iext_realloc_indirect(xfs_ifork_t *, int);
+void            xfs_iext_indirect_to_direct(xfs_ifork_t *);
 void            xfs_iext_direct_to_inline(xfs_ifork_t *, xfs_extnum_t);
 void            xfs_iext_inline_to_direct(xfs_ifork_t *, int);
 void            xfs_iext_destroy(xfs_ifork_t *);
+xfs_ext_irec_t  *xfs_iext_bno_to_irec(xfs_ifork_t *, xfs_fileoff_t, int *);
+xfs_ext_irec_t  *xfs_iext_idx_to_irec(xfs_ifork_t *, xfs_extnum_t *, int *, int);
+void            xfs_iext_irec_init(xfs_ifork_t *);
+xfs_ext_irec_t *xfs_iext_irec_new(xfs_ifork_t *, int);
+void            xfs_iext_irec_remove(xfs_ifork_t *, int);
+void            xfs_iext_irec_compact(xfs_ifork_t *);
+void            xfs_iext_irec_compact_pages(xfs_ifork_t *);
+void            xfs_iext_irec_compact_full(xfs_ifork_t *);
+void            xfs_iext_irec_update_extoffs(xfs_ifork_t *, int, int);
 
 #define xfs_ipincount(ip)       ((unsigned int) atomic_read(&ip->i_pincount))