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/**************************************************************************/
/* */
/* Copyright (c) Microsoft Corporation. All rights reserved. */
/* */
/* This software is licensed under the Microsoft Software License */
/* Terms for Microsoft Azure RTOS. Full text of the license can be */
/* found in the LICENSE file at https://aka.ms/AzureRTOS_EULA */
/* and in the root directory of this software. */
/* */
/**************************************************************************/
/**************************************************************************/
/**************************************************************************/
/** */
/** FileX Component */
/** */
/** Fault Tolerant */
/** */
/**************************************************************************/
/**************************************************************************/
#define FX_SOURCE_CODE
#include "fx_api.h"
#include "fx_utility.h"
#include "fx_fault_tolerant.h"
#ifdef FX_ENABLE_FAULT_TOLERANT
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _fx_fault_tolerant_cleanup_FAT_chain PORTABLE C */
/* 6.1 */
/* AUTHOR */
/* */
/* William E. Lamie, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function cleans up FAT chain. In order to prevent failures */
/* during the link-list walk, and to improve efficiency, this function */
/* frees the FAT entry chain in sections. For each section, it frees */
/* FAT entry from the last entry in the chain and works backwards. */
/* Using this method, if the system fails in the middle of the free */
/* operation, the head is preserved, and fault tolerant module can */
/* "redo" this operation next time it starts up. */
/* */
/* INPUT */
/* */
/* media_ptr Media control block pointer */
/* operation Recover a failure operation or*/
/* cleanup old FAT chain */
/* */
/* OUTPUT */
/* */
/* return status */
/* */
/* CALLS */
/* */
/* _fx_utility_exFAT_cluster_state_get Get state of exFAT cluster */
/* _fx_utility_exFAT_cluster_state_set Set state of exFAT cluster */
/* _fx_utility_FAT_entry_read Read a FAT entry */
/* _fx_utility_FAT_entry_write Write a FAT entry */
/* _fx_utility_16_unsigned_write Write a USHORT from memory */
/* _fx_utility_32_unsigned_write Write a ULONG from memory */
/* _fx_utility_32_unsigned_read Read a ULONG from memory */
/* _fx_utility_exFAT_bitmap_flush Flush exFAT allocation bitmap */
/* _fx_utility_FAT_flush Flush written FAT entries */
/* _fx_fault_tolerant_calculate_checksum Compute Checksum of data */
/* _fx_fault_tolerant_write_log_file Write log file */
/* */
/* CALLED BY */
/* */
/* _fx_fault_tolerant_apply_logs */
/* _fx_fault_tolerant_recover */
/* */
/* RELEASE HISTORY */
/* */
/* DATE NAME DESCRIPTION */
/* */
/* 05-19-2020 William E. Lamie Initial Version 6.0 */
/* 09-30-2020 William E. Lamie Modified comment(s), */
/* resulting in version 6.1 */
/* */
/**************************************************************************/
UINT _fx_fault_tolerant_cleanup_FAT_chain(FX_MEDIA *media_ptr, UINT operation)
{
UINT status;
ULONG current_cluster;
ULONG next_cluster = 0;
ULONG head_cluster;
ULONG tail_cluster;
ULONG cache_count;
ULONG cache_max = FX_FAULT_TOLERANT_CACHE_SIZE >> 2;
ULONG *cache_ptr = media_ptr -> fx_media_fault_tolerant_cache;
ULONG next_session;
USHORT checksum;
ULONG i;
FX_FAULT_TOLERANT_FAT_CHAIN *FAT_chain;
ULONG FAT_sector;
ULONG last_FAT_sector;
/* Set FAT chain pointer. */
FAT_chain = (FX_FAULT_TOLERANT_FAT_CHAIN *)(media_ptr -> fx_media_fault_tolerant_memory_buffer + FX_FAULT_TOLERANT_FAT_CHAIN_OFFSET);
/* Get head and tail cluster. */
if (operation == FX_FAULT_TOLERANT_FAT_CHAIN_RECOVER)
{
/* Recover phase. Cleanup (remove) new FAT chain. */
head_cluster = _fx_utility_32_unsigned_read((UCHAR *)&FAT_chain -> fx_fault_tolerant_FAT_chain_head_new);
}
else
{
/* Cleanup phase. Cleanup (remove) old FAT chain. */
head_cluster = _fx_utility_32_unsigned_read((UCHAR *)&FAT_chain -> fx_fault_tolerant_FAT_chain_head_original);
}
/* At this point, the head_cluster points to the cluster chain that is to be removed. */
/* Tail cluster points to the back of the origianl FAT chain where the new chain is attached to.
The remove process terminates once this cluster is encountered. */
tail_cluster = _fx_utility_32_unsigned_read((UCHAR *)&FAT_chain -> fx_fault_tolerant_FAT_chain_insertion_back);
/* Are there any clusters to free? */
if ((head_cluster < FX_FAT_ENTRY_START) || (head_cluster >= media_ptr -> fx_media_fat_reserved))
{
return(FX_SUCCESS);
}
/* To opimize the deletion process of a long FAT chain, the deletion is done in sessions. During one session,
a set of FAT entries are removed. If one session is interrupted, after restart the deletion process resumes and
picks up from where it left.
During one deletion session, all FAT entries are between head_cluster(inclusive) and next_session (exclusive).
*/
next_session = _fx_utility_32_unsigned_read((UCHAR *)&FAT_chain -> fx_fault_tolerant_FAT_chain_next_deletion);
/* Loop to cleanup all FAT entries. */
while ((head_cluster >= FX_FAT_ENTRY_START) && (head_cluster < media_ptr -> fx_media_fat_reserved))
{
/* Initialize. */
current_cluster = head_cluster;
cache_count = 0;
/* Loop from head cluster to find entries to cleanup and store this information into cache. */
do
{
/* Get the next FAT entry. */
status = _fx_utility_FAT_entry_read(media_ptr, current_cluster, &next_cluster);
if (status != FX_SUCCESS)
{
/* Return the error status. */
return(status);
}
/* Whether or not the cluster is occupied. */
if (next_cluster == FX_FREE_CLUSTER)
{
/* Current cluster has already been released. */
break;
}
/* Cache the FAT list. */
cache_ptr[cache_count++] = current_cluster;
/* Move to next cluster. */
current_cluster = next_cluster;
} while ((next_cluster >= FX_FAT_ENTRY_START) &&
(next_cluster < media_ptr -> fx_media_fat_reserved) &&
(next_cluster != tail_cluster) &&
(cache_count < cache_max));
/* Get next session. */
if (cache_count == cache_max)
{
next_session = next_cluster;
}
/* Update head cluster and next session into log file. */
_fx_utility_32_unsigned_write((UCHAR *)&FAT_chain -> fx_fault_tolerant_FAT_chain_next_deletion, next_session);
if (operation == FX_FAULT_TOLERANT_FAT_CHAIN_RECOVER)
{
_fx_utility_32_unsigned_write((UCHAR *)&FAT_chain -> fx_fault_tolerant_FAT_chain_head_new, head_cluster);
}
else
{
_fx_utility_32_unsigned_write((UCHAR *)&FAT_chain -> fx_fault_tolerant_FAT_chain_head_original, head_cluster);
}
/* Update checksum. */
_fx_utility_16_unsigned_write((UCHAR *)&FAT_chain -> fx_fault_tolerant_FAT_chain_checksumm, 0);
checksum = _fx_fault_tolerant_calculate_checksum((UCHAR *)FAT_chain, FX_FAULT_TOLERANT_FAT_CHAIN_SIZE);
_fx_utility_16_unsigned_write((UCHAR *)&FAT_chain -> fx_fault_tolerant_FAT_chain_checksumm, checksum);
/* Flush the fault tolerant log into the file system. */
_fx_fault_tolerant_write_log_file(media_ptr, 0);
/* Loop to free FAT in cache from back to front. */
if (cache_count > 0)
{
/* Get sector of last FAT entry. */
last_FAT_sector = _fx_utility_FAT_sector_get(media_ptr, cache_ptr[cache_count - 1]);
i = cache_count;
while (i > 0)
{
i--;
/* Get sector of current FAT entry. */
FAT_sector = _fx_utility_FAT_sector_get(media_ptr, cache_ptr[i]);
if (FAT_sector != last_FAT_sector)
{
/* Current FAT entry is located in different sector. Force flush. */
/* Flush the cached individual FAT entries */
_fx_utility_FAT_flush(media_ptr);
#ifdef FX_ENABLE_EXFAT
if (media_ptr -> fx_media_FAT_type == FX_exFAT)
{
/* Flush exFAT bitmap. */
_fx_utility_exFAT_bitmap_flush(media_ptr);
}
#endif /* FX_ENABLE_EXFAT */
/* Update sector of current FAT entry. */
last_FAT_sector = FAT_sector;
}
/* Free current_cluster. */
status = _fx_utility_FAT_entry_write(media_ptr, cache_ptr[i], FX_FREE_CLUSTER);
if (status != FX_SUCCESS)
{
/* Return the error status. */
return(status);
}
#ifdef FX_ENABLE_EXFAT
if (media_ptr -> fx_media_FAT_type == FX_exFAT)
{
/* Free bitmap. */
status = _fx_utility_exFAT_cluster_state_set(media_ptr, cache_ptr[i], FX_EXFAT_BITMAP_CLUSTER_FREE);
if (status != FX_SUCCESS)
{
/* Return the error status. */
return(status);
}
}
#endif /* FX_ENABLE_EXFAT */
}
/* Increase the available clusters in the media control block. */
media_ptr -> fx_media_available_clusters += cache_count;
}
/* Flush the cached individual FAT entries */
_fx_utility_FAT_flush(media_ptr);
#ifdef FX_ENABLE_EXFAT
if (media_ptr -> fx_media_FAT_type == FX_exFAT)
{
/* Flush exFAT bitmap. */
_fx_utility_exFAT_bitmap_flush(media_ptr);
}
#endif /* FX_ENABLE_EXFAT */
/* Get head cluster. */
if (head_cluster == next_session)
{
break;
}
head_cluster = next_session;
}
return(FX_SUCCESS);
}
#endif /* FX_ENABLE_FAULT_TOLERANT */
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