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authorLinus Torvalds <torvalds@linux-foundation.org>2009-09-14 14:35:56 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-09-14 14:35:56 -0700
commit33f1de69312432baecb997a570b7d77c4d02d1ed (patch)
tree24e9e7487ec3b892e120409aa2ac1b1263794373 /include
parent041d6d0be82bed7e0b87181dba5d10b8ab14afd9 (diff)
parent86d006365610fe6cda243d89b67d5047dca44656 (diff)
Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/steve/gfs2-2.6-nmw
* 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/steve/gfs2-2.6-nmw: GFS2: Whitespace fixes GFS2: Remove unused sysfs file GFS2: Be extra careful about deallocating inodes GFS2: Remove no_formal_ino generating code GFS2: Rename eattr.[ch] as xattr.[ch] GFS2: Clean up of extended attribute support GFS2: Add explanation of extended attr on-disk format GFS2: Add "-o errors=panic|withdraw" mount options GFS2: jumping to wrong label? GFS2: free disk inode which is deleted by remote node -V2 GFS2: Add a document explaining GFS2's uevents GFS2: Add sysfs link to device GFS2: Replace assertion with proper error handling GFS2: Improve error handling in inode allocation GFS2: Add some more info to uevents GFS2: Add online uevent to GFS2
Diffstat (limited to 'include')
-rw-r--r--include/linux/gfs2_ondisk.h22
1 files changed, 22 insertions, 0 deletions
diff --git a/include/linux/gfs2_ondisk.h b/include/linux/gfs2_ondisk.h
index c56b4bce56d..b80c88dedbb 100644
--- a/include/linux/gfs2_ondisk.h
+++ b/include/linux/gfs2_ondisk.h
@@ -333,6 +333,28 @@ struct gfs2_leaf {
/*
* Extended attribute header format
+ *
+ * This works in a similar way to dirents. There is a fixed size header
+ * followed by a variable length section made up of the name and the
+ * associated data. In the case of a "stuffed" entry, the value is
+ * inline directly after the name, the ea_num_ptrs entry will be
+ * zero in that case. For non-"stuffed" entries, there will be
+ * a set of pointers (aligned to 8 byte boundary) to the block(s)
+ * containing the value.
+ *
+ * The blocks containing the values and the blocks containing the
+ * extended attribute headers themselves all start with the common
+ * metadata header. Each inode, if it has extended attributes, will
+ * have either a single block containing the extended attribute headers
+ * or a single indirect block pointing to blocks containing the
+ * extended attribure headers.
+ *
+ * The maximim size of the data part of an extended attribute is 64k
+ * so the number of blocks required depends upon block size. Since the
+ * block size also determines the number of pointers in an indirect
+ * block, its a fairly complicated calculation to work out the maximum
+ * number of blocks that an inode may have relating to extended attributes.
+ *
*/
#define GFS2_EA_MAX_NAME_LEN 255