LU-9538 utils: update description of ldiskfs xattrs

[fs/lustre-release.git] / lustre / utils / libmount_utils_ldiskfs.c

diff --git a/lustre/utils/libmount_utils_ldiskfs.c b/lustre/utils/libmount_utils_ldiskfs.c
index ede2207..5fece46 100644 (file)
--- a/lustre/utils/libmount_utils_ldiskfs.c
+++ b/lustre/utils/libmount_utils_ldiskfs.c
@@ -739,24 +739,26 @@ int ldiskfs_make_lustre(struct mkfs_opts *mop)
                 * (assuming all files are in composite layout and has
                 * 3 components):
                 *
-                *   ldiskfs inode size: 156
-                *   extended attributes size, including:
+                *   ldiskfs inode size: 160
+                *   MDT extended attributes size, including:
                 *      ext4_xattr_header: 32
                 *      LOV EA size: 32(lov_comp_md_v1) +
                 *                   3 * 40(lov_comp_md_entry_v1) +
                 *                   3 * 32(lov_mds_md) +
                 *                   stripes * 24(lov_ost_data) +
-                *                   16(xattr_entry) + 3(lov)
+                *                   16(xattr_entry) + 4("lov")
                 *      LMA EA size: 24(lustre_mdt_attrs) +
-                *                   16(xattr_entry) + 3(lma)
+                *                   16(xattr_entry) + 4("lma")
+                *      SOM EA size: 24(lustre_som_attrs) +
+                *                   16(xattr_entry) + 4("som")
                 *      link EA size: 24(link_ea_header) + 18(link_ea_entry) +
-                *                    (filename) + 16(xattr_entry) + 4(link)
+                *                    16(filename) + 16(xattr_entry) + 4("link")
                 *   and some margin for 4-byte alignment, ACLs and other EAs.
                 *
                 * If we say the average filename length is about 32 bytes,
                 * the calculation looks like:
-                * 156 + 32 + (32+3*(40 + 32)+24*N+19) + (24+19) +
-                * (24+18+~32+20) + other <= 512*2^m, {m=0,1,2,3}
+                * 160 + 32 + (32+3*(40+32)+24*stripes+20) + (24+20) + (24+20) +
+                *  (24+20) + (~42+16+20) + other <= 512*2^m, {m=0,1,2,3}
                 */
                if (strstr(mop->mo_mkfsopts, "-I") == NULL) {
                        if (IS_MDT(&mop->mo_ldd)) {
@@ -769,7 +771,16 @@ int ldiskfs_make_lustre(struct mkfs_opts *mop)
                                        inode_size = 1024;
                        } else if (IS_OST(&mop->mo_ldd)) {
                                /* We store MDS FID and necessary composite
-                                * layout information in the OST object EA. */
+                                * layout information in the OST object EA:
+                                *   ldiskfs inode size: 160
+                                *   OST extended attributes size, including:
+                                *      ext4_xattr_header: 32
+                                *      LMA EA size: 24(lustre_mdt_attrs) +
+                                *                   16(xattr_entry) + 4("lma")
+                                *      FID EA size: 52(filter_fid) +
+                                *                   16(xattr_entry) + 4("fid")
+                                * 160 + 32 + (24+20) + (52+20) = 308
+                                */
                                inode_size = 512;
                        }