transactions such as unlink or ownership changes, configuration records
for targets and clients, or ChangeLog records to track changes to the
filesystem for external consumption, among others.
-
-Each llog file begins with an 'llog_log_hdr' that describes the llog
-file itself, followed by a series of log records that are appended
-sequentially to the file. Each record, including the header itself,
-begins with an 'llog_rec_hdr' and ends with an 'llog_rec_tail'.
-
-LLOG Log ID
-^^^^^^^^^^^
-[[struct-llog-logid]]
-
-----
-struct llog_logid {
- struct ost_id lgl_oi;
- __u32 lgl_ogen;
-};
-----
-
-The 'llog_logid' structure is used to identify a single Lustre log file.
-It holds a <<struct-ost-id>> in 'lgl_oi', which is typically a FID.
-
-LLog Information
-^^^^^^^^^^^^^^^^
-[[struct-llogd-body]]
-----
-struct llogd_body {
- struct llog_logid lgd_logid;
- __u32 lgd_ctxt_idx;
- __u32 lgd_llh_flags;
- __u32 lgd_index;
- __u32 lgd_saved_index;
- __u32 lgd_len;
- __u64 lgd_cur_offset;
-};
-----
-
-The lgd_llh_flags are:
-----
-enum llog_flag {
- LLOG_F_ZAP_WHEN_EMPTY = 0x1,
- LLOG_F_IS_CAT = 0x2,
- LLOG_F_IS_PLAIN = 0x4,
-};
-----
-
-LLog Record Header
-^^^^^^^^^^^^^^^^^^
-[[struct-llog-rec-hdr]]
-----
-struct llog_rec_hdr {
- __u32 lrh_len;
- __u32 lrh_index;
- __u32 lrh_type;
- __u32 lrh_id;
-};
-----
-
-The 'llog_rec_hdr' is at the start of each llog record and describes
-the log record. 'lrh_len' holds the record size in bytes, including
-the header and tail. 'lrh_index' is the record index within the llog
-file and is sequentially increasing for each subsequent record. It
-can be used to determine the offset within the llog file when searching
-for an arbitrary record within the file. 'lrh_type' describes the type
-of data stored in this record.
-
-----
-enum llog_op_type {
- LLOG_PAD_MAGIC = LLOG_OP_MAGIC | 0x00000,
- OST_SZ_REC = LLOG_OP_MAGIC | 0x00f00,
- MDS_UNLINK64_REC = LLOG_OP_MAGIC | 0x90000 | (MDS_REINT << 8) |
- REINT_UNLINK,
- MDS_SETATTR64_REC = LLOG_OP_MAGIC | 0x90000 | (MDS_REINT << 8) |
- REINT_SETATTR,
- OBD_CFG_REC = LLOG_OP_MAGIC | 0x20000,
- LLOG_GEN_REC = LLOG_OP_MAGIC | 0x40000,
- CHANGELOG_REC = LLOG_OP_MAGIC | 0x60000,
- CHANGELOG_USER_REC = LLOG_OP_MAGIC | 0x70000,
- HSM_AGENT_REC = LLOG_OP_MAGIC | 0x80000,
- UPDATE_REC = LLOG_OP_MAGIC | 0xa0000,
- LLOG_HDR_MAGIC = LLOG_OP_MAGIC | 0x45539,
- LLOG_LOGID_MAGIC = LLOG_OP_MAGIC | 0x4553b,
-};
-----
-
-LLog Record Tail
-^^^^^^^^^^^^^^^^
-[[struct-llog-rec-tail]]
-----
-struct llog_rec_tail {
- __u32 lrt_len;
- __u32 lrt_index;
-};
-----
-
-The 'llog_rec_tail' is at the end of each llog record. The 'lrt_len'
-and 'lrt_index' fields must be the same as 'lrh_len' and 'lrh_index'
-in the header. They can be used to verify record integrity, as well
-as allowing processing the llog records in reverse order.
-
-LLog Log Header Information
-^^^^^^^^^^^^^^^^^^^^^^^^^^^
-[[struct-llog-log-hdr]]
-----
-struct llog_log_hdr {
- struct llog_rec_hdr llh_hdr;
- obd_time llh_timestamp;
- __u32 llh_count;
- __u32 llh_bitmap_offset;
- __u32 llh_size;
- __u32 llh_flags;
- __u32 llh_cat_idx;
- /* for a catalog the first plain slot is next to it */
- struct obd_uuid llh_tgtuuid;
- __u32 llh_reserved[LLOG_HEADER_SIZE/sizeof(__u32) - 23];
- __u32 llh_bitmap[LLOG_BITMAP_BYTES/sizeof(__u32)];
- struct llog_rec_tail llh_tail;
-};
-----
-
-The llog records start and end on a record size boundary, typically
-8192 bytes, or as stored in 'llh_size', which allows some degree of
-random access within the llog file, even with variable record sizes.
-It is possible to interpolate the offset of an arbitrary record
-within the file by estimating the byte offset of a particular record
-index using 'llh_count' and the llog file size and aligning it to
-the chunk boundary 'llh_size'. The record index in the 'llog_rec_hdr'
-of the first record in that chunk can be used to further refine the
-estimate of the offset of the desired index down to a single chunk,
-and then sequential access can be used to find the actual record.
-
git://git.whamcloud.com / doc / protocol.git / blobdiff