.TH LUSTREAPI 7 2026-09-03 "Lustre User API" "The Lustre API library"
.SH NAME
lustreapi \- The Lustre API library
.SH SYNOPSIS
.nf
.B #include <lustre/lustreapi.h>
.fi
.SH DESCRIPTION
The lustreapi library provides functions to access and/or modify
settings specific to the Lustre filesystem (allocation policies,
quotas, file layouts, etc).  See the referenced man pages for details.
.SH AUTHORS
Lustre contributors
.SH AVAILABILITY
.B lustreapi
is part of the
.BR lustre (7)
user application interface library since release 0.10.0
.\" Added in commit 0.9.1
.SH SEE ALSO
.SS Changelogs
Functions for accessing and managing Lustre changelogs.
.PP
.BR llapi_changelog_clear (3),
.BR llapi_changelog_fini (3),
.BR llapi_changelog_free (3),
.BR llapi_changelog_get_fd (3),
.BR llapi_changelog_in_buf (3),
.BR llapi_changelog_recv (3),
.BR llapi_changelog_set_xflags (3),
.BR llapi_changelog_start (3),
.BR llapi_changelog_start_user (3)
.SS Directory Operations
Functions for creating and managing Lustre directories.
.PP
.BR llapi_dir_create (3),
.BR llapi_dir_create_foreign (3),
.BR llapi_dir_create_pool (3)
.SS FID Handling
Functions for working with Lustre File Identifiers (FIDs).
.PP
.BR llapi_fd2fid (3),
.BR llapi_fd2parent (3),
.BR llapi_fid_hash (3),
.BR llapi_fid_parse (3),
.BR llapi_fid_to_handle (3),
.BR llapi_fid2path (3),
.BR llapi_fid2path_at (3),
.BR llapi_path2fid (3),
.BR llapi_path2parent (3),
.BR llapi_rmfid (3),
.BR llapi_rmfid_at (3)
.SS File Operations
Functions for creating and managing Lustre files.
.PP
.BR llapi_file_create (3),
.BR llapi_file_create_foreign (3),
.BR llapi_file_get_stripe (3),
.BR llapi_file_open (3),
.BR llapi_file_open_volatile (3),
.BR llapi_fsync (3),
.BR llapi_open_by_fid (3),
.BR llapi_open_by_fid_at (3),
.BR llapi_unlink_foreign (3)
.SS File Layouts and Striping
Functions for file layouts and striping across OSTs.
.PP
.BR llapi_layout_alloc (3),
.BR llapi_layout_comp_add (3),
.BR llapi_layout_comp_del (3),
.BR llapi_layout_comp_extent_get (3),
.BR llapi_layout_comp_extent_set (3),
.BR llapi_layout_comp_flags_clear (3),
.BR llapi_layout_comp_flags_get (3),
.BR llapi_layout_comp_flags_set (3),
.BR llapi_layout_comp_id_get (3),
.BR llapi_layout_comp_use (3),
.BR llapi_layout_comp_use_id (3),
.BR llapi_layout_extension_size_get (3),
.BR llapi_layout_extension_size_set (3),
.BR llapi_layout_file_comp_add (3),
.BR llapi_layout_file_comp_del (3),
.BR llapi_layout_file_create (3),
.BR llapi_layout_file_open (3),
.BR llapi_layout_file_open_volatile (3),
.BR llapi_layout_free (3),
.BR llapi_layout_get_by_fd (3),
.BR llapi_layout_get_by_fid (3),
.BR llapi_layout_get_by_path (3),
.BR llapi_layout_get_by_xattr (3),
.BR llapi_layout_ost_index_get (3),
.BR llapi_layout_ost_index_reset (3),
.BR llapi_layout_ost_index_set (3),
.BR llapi_layout_pattern_get (3),
.BR llapi_layout_pattern_set (3),
.BR llapi_layout_pool_name_get (3),
.BR llapi_layout_pool_name_set (3),
.BR llapi_layout_set_by_fd (3),
.BR llapi_layout_set_by_xattr (3),
.BR llapi_layout_stripe_count_get (3),
.BR llapi_layout_stripe_count_set (3),
.BR llapi_layout_stripe_size_get (3),
.BR llapi_layout_stripe_size_set (3)
.SS Filesystem Information
Functions for querying filesystem names and paths.
.PP
.BR llapi_get_fsname (3),
.BR llapi_get_fsname_instance (3),
.BR llapi_get_instance (3),
.BR llapi_get_lum_dir (3),
.BR llapi_get_lum_dir_fd (3),
.BR llapi_get_lum_file (3),
.BR llapi_get_lum_file_fd (3),
.BR llapi_get_mdt_index_by_fid (3),
.BR llapi_getname (3),
.BR llapi_lmv_get_uuids (3),
.BR llapi_lov_get_uuids (3)
.SS Hierarchical Storage Management (HSM)
Functions for HSM copytool operations and archive management.
.PP
.BR llapi_hsm_action_begin (3),
.BR llapi_hsm_action_end (3),
.BR llapi_hsm_action_get_dfid (3),
.BR llapi_hsm_action_get_fd (3),
.BR llapi_hsm_action_progress (3),
.BR llapi_hsm_copytool_get_fd (3),
.BR llapi_hsm_copytool_recv (3),
.BR llapi_hsm_copytool_register (3),
.BR llapi_hsm_copytool_unregister (3),
.BR llapi_hsm_data_version_set (3),
.BR llapi_hsm_state_get (3),
.BR llapi_hsm_state_set (3)
.SS Namespace Scanning
Functions for walking a filesystem and reporting a record per object.
.PP
.BR llapi_scan_namespace (3)
.SS Persistent Client Cache (PCC)
Functions for managing Persistent Client Cache operations.
.PP
.BR llapi_pcc_attach (3),
.BR llapi_pcc_attach_fid (3),
.BR llapi_pcc_attach_fid_str (3),
.BR llapi_pcc_clear (3),
.BR llapi_pcc_del (3),
.BR llapi_pcc_detach_fid (3),
.BR llapi_pcc_detach_fid_fd (3),
.BR llapi_pcc_detach_fid_str (3),
.BR llapi_pcc_detach_file (3),
.BR llapi_pcc_state_get (3),
.BR llapi_pcc_state_get_fd (3),
.BR llapi_pccdev_get (3),
.BR llapi_pccdev_set (3)
.SS Pool Operations
Functions for managing OST pools.
.PP
.BR llapi_pool_is_pinned_fd (3),
.BR llapi_pool_is_pinned_fid (3),
.BR llapi_pool_is_pinned_file (3),
.BR llapi_pool_pin_fd (3),
.BR llapi_pool_pin_fid (3),
.BR llapi_pool_pin_file (3),
.BR llapi_pool_unpin_fd (3),
.BR llapi_pool_unpin_fid (3),
.BR llapi_pool_unpin_file (3)
.SS Project Management
Functions for managing project IDs and quotas.
.PP
.BR llapi_project_close (3),
.BR llapi_project_fgetnam (3),
.BR llapi_project_fgetprjid (3),
.BR llapi_project_get (3),
.BR llapi_project_getnam (3),
.BR llapi_project_getprjid (3),
.BR llapi_project_open (3),
.BR llapi_project_put (3),
.BR llapi_quotactl (3)
.SS Target Search
Functions for searching MDTs and OSTs.
.PP
.BR llapi_search_mdt (3),
.BR llapi_search_ost (3),
.BR llapi_search_rootpath (3),
.BR llapi_search_rootpath_by_dev (3),
.BR llapi_search_tgt (3)
.SS Tunable Parameters
Functions for accessing and modifying Lustre tunable parameters.
.PP
.BR llapi_param_get_paths (3),
.BR llapi_param_get_value (3)
.SS Miscellaneous
Other utility functions.
.PP
.BR llapi_convert_str2mask (3),
.BR llapi_find_param_alloc (3),
.BR llapi_find_param_free (3),
.BR llapi_get_data_version (3),
.BR llapi_get_obd_count (3),
.BR llapi_group_lock (3),
.BR llapi_group_unlock (3),
.BR llapi_heat_get (3),
.BR llapi_heat_set (3),
.BR llapi_ioctl (3),
.BR llapi_ladvise (3),
.BR llapi_lov_pattern_string (3),
.BR llapi_lov_string_pattern (3),
.BR llapi_root_path_open (3),
.BR lustre (7)