diff options
Diffstat (limited to 'src/H5FS.c')
| -rw-r--r-- | src/H5FS.c | 163 |
1 files changed, 163 insertions, 0 deletions
@@ -901,6 +901,169 @@ done: /*------------------------------------------------------------------------- + * Function: H5FS_alloc_vfd_alloc_hdr_and_section_info + * + * Purpose: This function is part of a hack to patch over a design + * flaw in the free space managers for file space allocation. + * Specifically, if a free space manager allocates space for + * its own section info, it is possible for it to + * go into an infinite loop as it: + * + * 1) computes the size of the section info + * + * 2) allocates file space for the section info + * + * 3) notices that the size of the section info + * has changed + * + * 4) deallocates the section info file space and + * returns to 1) above. + * + * Similarly, if it allocates space for its own header, it + * can go into an infinte loop as it: + * + * 1) allocates space for the header + * + * 2) notices that the free space manager is empty + * and thus should not have file space allocated + * to its header + * + * 3) frees the space allocated to the header + * + * 4) notices that the free space manager is not + * empty and thus must have file space allocated + * to it, and thus returns to 1) above. + * + * In a nutshell, the solution applied in this hack is to + * deallocate file space for the free space manager(s) that + * handle FSM header and/or section info file space allocations, + * wait until all other allocation/deallocation requests have + * been handled, and then test to see if the free space manager(s) + * in question are empty. If they are, do nothing. If they + * are not, allocate space for them at end of file bypassing the + * usual file space allocation calls, and thus avoiding the + * potential infinite loops. + * + * The purpose of this function is to allocate file space for + * the header and section info of the target free space manager + * directly from the VFD if needed. In this case the function + * also re-inserts the header and section info in the metadata + * cache with this allocation. + * + * Note that if f->shared->alignment > 1, and EOA is not a + * multiple of the alignment, it is possible that performing + * this allocation may generate a fragment of file space in + * addition to the space allocated for the section info. + * + * At present we deal with this by screaming and dying. + * Obviously, this is not acceptatable, but it should do + * for now. + * + * + * Return: Success: non-negative + * Failure: negative + * + * Programmer: John Mainzer + * 6/6/16 + * + *------------------------------------------------------------------------- + */ +herr_t +H5FS_alloc_vfd_alloc_hdr_and_section_info(H5F_t *f, hid_t dxpl_id, + H5FS_t *fspace, haddr_t *fs_addr_ptr) +{ + herr_t ret_value = SUCCEED; /* Return value */ + + FUNC_ENTER_NOAPI_TAG(dxpl_id, H5AC__FREESPACE_TAG, FAIL) + + /* Check arguments */ + HDassert(f); + HDassert(fspace); + HDassert(fs_addr_ptr); + + /* The section info should be unlocked */ + HDassert(fspace->sinfo_lock_count == 0); + + /* No space should be allocated */ + HDassert(*fs_addr_ptr == HADDR_UNDEF); + HDassert(fspace->addr == HADDR_UNDEF); + HDassert(fspace->sect_addr == HADDR_UNDEF); + HDassert(fspace->alloc_sect_size == 0); + + /* Check if any space will be needed */ + if(fspace->serial_sect_count > 0) { + haddr_t sect_addr; /* Address of sinfo */ + + /* The section info is floating, so fspace->sinfo should be defined */ + HDassert(fspace->sinfo); + + /* Start by allocating file space for the header */ + if(HADDR_UNDEF == (fspace->addr = H5MF_vfd_alloc(f, dxpl_id, H5FD_MEM_FSPACE_HDR, + (hsize_t)H5FS_HEADER_SIZE(f), FALSE))) + HGOTO_ERROR(H5E_FSPACE, H5E_CANTALLOC, FAIL, "can't allocate file space for hdr") + + /* Cache the new free space header (pinned) */ + if(H5AC_insert_entry(f, dxpl_id, H5AC_FSPACE_HDR, fspace->addr, fspace, H5AC__PIN_ENTRY_FLAG) < 0) + HGOTO_ERROR(H5E_FSPACE, H5E_CANTINSERT, FAIL, "can't add free space header to cache") + + + /* Now allocate file space for the section info */ + if(HADDR_UNDEF == (sect_addr = H5MF_vfd_alloc(f, dxpl_id, H5FD_MEM_FSPACE_SINFO, + fspace->sect_size, FALSE))) + HGOTO_ERROR(H5E_FSPACE, H5E_CANTALLOC, FAIL, "can't allocate file space") + + /* Update fspace->alloc_sect_size and fspace->sect_addr to reflect + * the allocation + */ + fspace->alloc_sect_size = fspace->sect_size; + fspace->sect_addr = sect_addr; + + /* We have changed the sinfo address -- Mark free space header dirty */ + if(H5AC_mark_entry_dirty(fspace) < 0) + HGOTO_ERROR(H5E_FSPACE, H5E_CANTMARKDIRTY, FAIL, "unable to mark free space header as dirty") + + /* Insert the new section info into the metadata cache. */ + + /* Question: Do we need to worry about this insertion causing an + * eviction from the metadata cache? Think on this. If so, add a + * flag to H5AC_insert() to force it to skip the call to make space in + * cache. + * + * On reflection, no. + * + * On a regular file close, any eviction will not change the + * the contents of the free space manger(s), as all entries + * should have correct file space allocated by the time this + * function is called. + * + * In the cache image case, the selection of entries for inclusion + * in the cache image will not take place until after this call. + * (Recall that this call is made during the metadata fsm settle + * routine, which is called during the serialization routine in + * the cache image case. Entries are not selected for inclusion + * in the image until after the cache is serialized.) + * + * JRM -- 11/4/16 + */ + if(H5AC_insert_entry(f, dxpl_id, H5AC_FSPACE_SINFO, sect_addr, fspace->sinfo, H5AC__NO_FLAGS_SET) < 0) + HGOTO_ERROR(H5E_FSPACE, H5E_CANTINSERT, FAIL, "can't add free space sinfo to cache") + + /* Since space has been allocated for the section info and the sinfo + * has been inserted into the cache, relinquish owership (i.e. float) + * the section info. + */ + fspace->sinfo = NULL; + + /* Set the address of the free space header, on success */ + *fs_addr_ptr = fspace->addr; + } /* end if */ + +done: + FUNC_LEAVE_NOAPI_TAG(ret_value, FAIL) +} /* H5FS_alloc_vfd_alloc_hdr_and_section_info() */ + + +/*------------------------------------------------------------------------- * Function: H5FS_free() * * Purpose: Free space for free-space manager header and section info header |