CN107037988B - A kind of flash memory safety deleting method and system based on file-level granularity - Google Patents
A kind of flash memory safety deleting method and system based on file-level granularity Download PDFInfo
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- CN107037988B CN107037988B CN201710219959.8A CN201710219959A CN107037988B CN 107037988 B CN107037988 B CN 107037988B CN 201710219959 A CN201710219959 A CN 201710219959A CN 107037988 B CN107037988 B CN 107037988B
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/06—Digital input from, or digital output to, record carriers, e.g. RAID, emulated record carriers or networked record carriers
- G06F3/0601—Interfaces specially adapted for storage systems
- G06F3/0602—Interfaces specially adapted for storage systems specifically adapted to achieve a particular effect
- G06F3/062—Securing storage systems
- G06F3/0623—Securing storage systems in relation to content
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/06—Digital input from, or digital output to, record carriers, e.g. RAID, emulated record carriers or networked record carriers
- G06F3/0601—Interfaces specially adapted for storage systems
- G06F3/0628—Interfaces specially adapted for storage systems making use of a particular technique
- G06F3/0646—Horizontal data movement in storage systems, i.e. moving data in between storage devices or systems
- G06F3/0652—Erasing, e.g. deleting, data cleaning, moving of data to a wastebasket
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/06—Digital input from, or digital output to, record carriers, e.g. RAID, emulated record carriers or networked record carriers
- G06F3/0601—Interfaces specially adapted for storage systems
- G06F3/0668—Interfaces specially adapted for storage systems adopting a particular infrastructure
- G06F3/0671—In-line storage system
- G06F3/0673—Single storage device
- G06F3/0679—Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]
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Abstract
The flash memory safety deleting method based on file-level granularity that the invention discloses a kind of, belongs to computer field of storage.The method of the present invention is that each file distributes a globally unique identifier GUID, and GUID is encapsulated to each write request and removal request of file, GUID-page adjacency list is constructed simultaneously, for recording the corresponding invalid physical page of each file in real time, when user deletes some file, equipment can find the corresponding all invalid physical pages of file and all effective Physical Page by delete command, then be override using the Physical Page overriding technology Physical Page all to file to achieve the purpose that safety deleting file.The flash memory safety deleting system based on file-level granularity that The invention also achieves a kind of.Technical solution of the present invention solves the problems, such as that the existing solid-state disk based on flash media efficiently safety deleting single file can not reduce influence of the safety deleting to readwrite performance on the basis of realizing solid-state disk safety deleting single file.
Description
Technical field
The invention belongs to computer field of storage, delete safely more particularly, to a kind of flash memory based on file-level granularity
Except method and system.
Background technique
With the development of data recovery technique, current computer systems have been difficult complete deletion file, at recovery
Remaining data on storage medium are managed, attacker can steal deleted confidential information, this has become threat storage system
The important hidden danger of information security.It is found in a survey report in 2016, (93% is mechanical from the second-hand hard disk of 200 muti-pieces
Hard disk, residue are SSD), discovery be more than 78% second-hand hard disk in there are remaining datas, wherein 67% hard disk can restore there emerged a
Man-machine confidential information, 11% hard disk include company sensitive data.In addition investigation display, 36% hard disk include residual data, i.e.,
User still has data remanence after having carried out delete operation；40% hard disk carried out formatting, but still had data remanence hard
In disk；Only only have 10% hard disk that safe erasing means was taken to clear data.This absolutely proves common deletion and lattice
Formulaization operation can not really delete data, and user needs that safety deleting means is taken to prevent leaking data.
Safety deleting refer to be deleted data in memory carrier by various technological means after it is irrecoverable, and set
It is standby can secondary use.Being directed to magnetic medium proposes a variety of safety deleting methods based on overriding at present, and main thought is to delete
When except file, corresponding LBA (logical block addresses) space of this document is rewritten, covering writes the physics for having file initial data and is situated between
Matter carrys out safety deleting file with this.But the characteristics of being updated due to flash memory strange land is deposited when the corresponding space LBA of rewriting this document
There is the Physical Page of file initial data that will become in vain, covering the data write and being written to new Physical Page, be unable to reach covering
The effect of written document initial data.Meanwhile after largely reading and writing, each data page of file is likely to that there are several
Copy, the time that these data page copies save in storage medium be it is uncertain, one can only be recycled in garbage reclamation
The information in deleted document while occupying solid-state disk space, has been revealed in part.Therefore, for the solid-state based on flash memory
Disk needs to introduce the new safety deleting technology of one kind to change this predicament.
The granularity of existing safety deleting method generally comprises four classes: page level security is deleted, block level security is deleted, file-level peace
Full deletion and overall safety deleting.Page grade safety deleting method as unit of single physical page, in real time safety deleting because
More newly generated invalid page is write, during the editor of file and modification, update is write and operates very frequent, the safety deleting of page grade
Method can seriously affect response of the solid-state disk to normal read-write requests；Block level security delet method is adopted as unit of physical block
With block erasing means come safety deleting physical block, when there are when active page, need to migrate active page to bring expense, and block in block
The practicability is poor for granularity；And the safety deleting of file-level is as unit of file, the delete operation of usual file infrequently, only with
When some file is deleted at family, safety deleting operation can be just triggered, the readwrite performance of solid-state disk is influenced small；Overall safety deleting is suitable
With narrow range, for the common application scenarios of multiple users share storage resource, being to entire physical disks progress safety deleting can not
It realizes, even carrying out the safety deleting that safety deleting also implies that some file to entire virtual disk.
For the solid-state disk based on flash memory, although cannot be by the way of the space LBA of overriding file come safety deleting text
Part, but directly physical medium can be override.For SLC Flash, someone is experiments prove that Physical Page to SLC Flash
It is feasible for carrying out secondary write-in, it can by common Physical Page writing commands, to the Physical Page of storage sensitive data into
Row covering write-in, to realize the safety deleting to SLC Flash.But additional Physical Page overwriting operations will affect flash memory to normal
The response of read-write requests, safety deleting invalid page will seriously affect the performance of solid-state disk in real time；And the file granularity of its proposition
Safety deleting method need to be traversed for all Physical Page of entire solid-state disk to determine the corresponding invalid page copy of file, be delayed non-
Chang great.
As shown in Figure 1: for MLC flash, support 4 kinds of voltage levels, each unit that can store 2bits, state change is tight
Lattice follow the raised rule of threshold voltage, cannot reversely change state before the erasing, i.e., the write operation inside MLC flash must
It must carry out in a certain order；
When carrying out safety deleting to the solid-state disk based on MLC flash, there are two limitations:
(1) influenced by programming interference, when the low page of MLC flash and all effective high page, cannot individually override low page or
Otherwise high page can destroy the data in high page or low page；
(2) error rate of each physical block of MLC flash increases with the Physical Page quantity being written and is risen, i.e., each object
Reason block can only bear part Physical Page and be written.
Due to these limitations, there are two types of traditional solutions: one is MLC flash is used as SLC Flash, first only
Using the low page in pairs of page (Paired Page), only after low page is invalid and is override, the low page could be used right
The high page answered, the serious capacity for wasting MLC flash；Another kind is, when needing to override some page in the pairs of page of MLC flash
When, first the data in another page in pairs of page to be migrated, then override this pairs of page, waste MLC flash capacity
While, safety deleting inefficiency；Therefore, simple Physical Page overwrite method is not appropriate for MLC flash.
Summary of the invention
Aiming at the above defects or improvement requirements of the prior art, the present invention provides a kind of flash memories based on file-level granularity
Safety deleting method and system, its object is to by file system layer be each file distribute a GUID number, the bottom of to
Layer transmitting the file information allows equipment to grasp the storage location of file data blocks, record the invalid of each file generation in real time
Physical Page；When user deletes some file, equipment can find the corresponding all invalid physical pages of file by delete command
With all effective Physical Page, then override using the Physical Page overwrite method Physical Page all to file to reach safety and delete
Except the purpose of file, the technical problem that existing flash memory safety deleting technical efficiency is low, delay is big is thus solved.
To achieve the above object, according to one aspect of the present invention, a kind of flash memory peace based on file-level granularity is provided
Full delet method, this method comprises:
(1) GUID distribution and encapsulation: a globally unique identifier GUID is distributed for each file, and by the GUID of file
Be encapsulated into file write in removal request；If write request, then (2) are entered step；If removal request then enters step
(5)；
(2) write-in medium judges: if storage medium is MLC flash, entering step (3)；Otherwise (4) are entered step；
(3) it distributes the pairs of page of MLC flash: finding the Physical Page position of this document last time write-in according to write request No. GUID
It sets, if low page, then distributes the corresponding high page of the low page to write request, the data block of file is made to be distributed in the pairs of physics of MLC
In page；If high page, then idle low page is distributed to write request；If distributing the free time after starting garbage reclamation without idle low page
Low page is to write request；
(4) it records the invalid page of file: recording the invalid physical that each file generates in real time using GUID-page table
Page；
(5) deletion medium judges: if storage medium is MLC flash, entering step (6)；If storage medium is SLC sudden strain of a muscle
It deposits, then enters step (7)；
(6) based on the safety deleting of MLC flash: it is corresponding to find file to be deleted according to GUID-page table and removal request
All Physical Page, the use overriding technology progress safety deleting of the not super upper limit of overriding number of physical block where Physical Page covers
It writes and physical block erasing is reached into safety deleting after the active page in the migration physical block of the super upper limit of number；
(7) based on the safety deleting of SLC Flash: finding the file pair to be deleted according to GUID-page table and removal request
All Physical Page answered reuse Physical Page overriding technology and carry out safety deleting to data in these Physical Page；
(8) safety deleting of metadata: the metadata modification request and mapping relations generated according to file delete operation
Modification, finds the Physical Page where metadata, carries out safety deleting to Physical Page where metadata.
Further, the step (3) specifically includes:
(31) Physical Page is inquired: being searched GUID-page table according to the GUID of write request, is found in corresponding GUID-page table
The physical page number for the page node that head node pointer is directed toward；
(32) page is judged: judges that the physical page number is low page, high page or physical page number initial value, if low page,
The corresponding high page of the low page is distributed to write request, enters step (35)；If high page or physical page number initial value, then judge
Whether available free low page if so, then distributing idle low page to write request enters step (34) in solid-state disk；Otherwise it enters step
(33)；
(33) garbage reclamation: the active page in the object block to be recycled first is migrated, while according to the corresponding GUID of active page
The physical page number for the page node that head node pointer is directed toward in corresponding GUID-page table is searched, if the physical page number of page node and having
The physical page number for imitating page is identical, then the physical page number of page node is changed to the physical page number after effective page migration；Otherwise it does not do and locates
Reason；Corresponding GUID-page table is searched according to the corresponding GUID of invalid page in object block later, deletes page knot in GUID-page table
The physical page number of point is equal to the page node of invalid page physical page number；Object block is wiped, the idle low page of distribution later is to write request；
(34) physical page number is updated: the physics for the page node that head node pointer in the GUID-page table of write request is directed toward
Page number is updated to newly distribute the physical page number of Physical Page.
Further, the step (4) specifically includes:
(41) it writes hit judgement: address mapping table is searched according to the logical address of write request, if hit, enters step
(42)；Otherwise (43) are entered step；
(42) it records invalid physical page: the state of old physical page is set to the page knot for distributing new GUID-page table in vain
The physical page number of point, page node is the old physical page number, and new page node is linked at the corresponding GUID-page of GUID of write request
Table tail portion；
(43) it updates address mapping table: updating address mapping table.
Further, the step (6) specifically includes:
(61) search invalid physical page: according to the GUID of removal request, the head node searched in corresponding GUID-page table refers to
The page node that needle is directed toward, all page nodes linked after the page node are invalid physical page node；
(62) it resets GUID-page table: according to the GUID of removal request, deleting all pages of knots in corresponding GUID-page table
Point, and head node is reinitialized；
(63) it searches effective Physical Page: the logical address of removal request and size is resolved into multiple logical page number (LPN)s, according to
Logical page number (LPN) searches address mapping table, finds corresponding effective physical page number, the state of the effective Physical Page found is set to nothing
Effect；
(64) overriding number judgement: for all Physical Page found, the overriding of physical block is counted where judging Physical Page
Whether be more than the physical block overriding maximum number of times；If being not above, (65) are entered step；Otherwise (66) are entered step；
(65) overriding is deleted: using data in Physical Page overriding technical security deletion of physically page；Physics where the Physical Page
Count is incremented for the overriding of block；
(66) physical block is wiped: migrating all effective Physical Page in the physical block where the Physical Page, while more cenotype
Address mapping table and GUID-page table are answered, the physical block is wiped later and realizes safety deleting.
Further, the step (7) specifically includes:
(71) safety deleting invalid physical page: according to the GUID of removal request, the head knot in corresponding GUID-page table is searched
The page node that pointer is directed toward is put, all page nodes linked after the page node are invalid physical page node, are covered using Physical Page
Data in writing technology safety deleting invalid physical page；
(72) it deletes page node: according to the GUID of removal request, deleting all page nodes in corresponding GUID-page table, and
Head node is reinitialized；
(73) the effective Physical Page of safety deleting: resolving to multiple logical page number (LPN)s for the logical address of removal request and size,
Address mapping table is searched according to logical page number (LPN), finds corresponding effective physical page number, is deleted using Physical Page overriding technical security
Except data in effective Physical Page；
(74) it updates address mapping table: the effective Physical Page found being set to invalid physical page, updates address mapping table.
It is another aspect of this invention to provide that providing a kind of flash memory safety deleting system based on file-level granularity, this is
System includes:
GUID distribution and package module, for distributing a globally unique identifier GUID for each file, and by file
GUID be encapsulated into file write in removal request；If write request, then enter write-in medium judgment module；If deletion is asked
It asks then to enter and deletes medium judgment module；
Medium judgment module is written, if entering the pairs of page distribution of MLC flash for judging storage medium as MLC flash
Module；Otherwise enter file is invalid page logging modle；
The pairs of page distribution module of MLC flash, for finding the object of this document last time write-in according to No. GUID of write request
Page position is managed, if low page, then the corresponding high page of the low page is distributed to write request, so that the data block of file is distributed in MLC pairs of
Physical Page in；If high page, then idle low page is distributed to write request；If dividing after starting garbage reclamation without free space
With idle low page to write request；
Page logging modle that file is invalid, for recording the invalid object that each file generates in real time using GUID-page table
Manage page；
Medium judgment module is deleted, if for judging that storage medium as MLC flash, enters the safety based on MLC flash
Removing module；If storage medium is SLC Flash, enter the safety deleting module based on SLC Flash；
Safety deleting module based on MLC flash, for finding file to be deleted according to GUID-page table and removal request
Corresponding all Physical Page, the not super upper limit of overriding number of physical block where Physical Page carry out safe delete using overriding technology
It removes, physical block erasing is reached into safety deleting after the active page in the migration physical block of the overriding super upper limit of number；
Safety deleting module based on SLC Flash, for finding the text to be deleted according to GUID-page table and removal request
The corresponding all Physical Page of part reuse Physical Page overriding technology and carry out safety deleting to data in these Physical Page；
The safety deleting module of metadata, metadata modification request and mapping for being generated according to file delete operation are closed
The Physical Page where metadata is found in the modification of system, carries out safety deleting to Physical Page where metadata.
Further, the pairs of page distribution module of the MLC flash specifically includes:
Physical Page query unit finds corresponding GUID-page for searching GUID-page table according to the GUID of write request
The physical page number for the page node that head node pointer is directed toward in table；
To page judging unit, for judging that the physical page number is low page, high page or physical page number initial value, if low
Page distributes the corresponding high page of the low page to write request, into update physical page number unit；If at the beginning of high page or physical page number
Initial value, then judge in solid-state disk whether available free low page, if so, then distributing idle low page to write request, into more new physical page
Number unit；Otherwise enter garbage reclamation unit；
Garbage reclamation unit: for first migrating the active page in the object block to be recycled, while in, active page is corresponding
GUID search the physical page number of the page node that head node pointer is directed toward in corresponding GUID-page table, if the Physical Page of page node
It is number identical with the physical page number of active page, then the physical page number of page node is changed to the physical page number after effective page migration；Otherwise
It is not processed；Corresponding GUID-page table is searched according to the corresponding GUID of invalid page in object block later, deletes GUID-page table
The physical page number of middle page node is equal to the page node of invalid page physical page number；Object block is wiped, the idle low page of distribution later is write
Request；
Physical page number unit is updated, for the page node of head node pointer direction in the GUID-page table by write request
Physical page number is updated to newly distribute the physical page number of Physical Page.
It is further, described that file is invalid that page logging modle specifically includes:
Hit judging unit is write, for searching address mapping table according to the logical address of write request, if hit, enters note
Record invalid physical page unit；Otherwise enter and update address of cache table unit；
Invalid physical page unit is recorded, distributes new GUID-page table in vain for the state of old physical page to be set to
The physical page number of page node, page node is the old physical page number, and new page node is linked at the corresponding GUID- of GUID of write request
Page table tail portion；
Address of cache table unit is updated, for updating address mapping table.
Further, the safety deleting module based on MLC flash specifically includes:
Invalid physical page unit is searched, for the GUID according to removal request, searches the head knot in corresponding GUID-page table
The page node that pointer is directed toward is put, all page nodes linked after the page node are invalid physical page node；
GUID-page table unit is reset, for the GUID according to removal request, deletes and owns in corresponding GUID-page table
Page node, and head node is reinitialized；
Effective Physical Page unit is searched, for the logical address of removal request and size to be resolved to multiple logical page number (LPN)s,
Address mapping table is searched according to logical page number (LPN), corresponding effective physical page number is found, the state of the effective Physical Page found is set
It is invalid；
Frequency judging unit is override, for judging the overriding of Physical Page place physical block for all Physical Page found
Count whether be more than the physical block overriding maximum number of times；If being not above, enters overriding and delete unit；Otherwise enter physics
Block wipes unit；
Unit is deleted in overriding, for using data in Physical Page overriding technical security deletion of physically page；Where the Physical Page
Count is incremented for the overriding of physical block；
Physical block wipes unit, for migrating all effective Physical Page in the physical block where the Physical Page, while more
New corresponding address mapping table and GUID-page table, wipe the physical block later and realize safety deleting.
Further, the safety deleting module based on SLC Flash specifically includes:
Safety deleting invalid physical page unit is searched in corresponding GUID-page table for the GUID according to removal request
The page node that head node pointer is directed toward, all page nodes linked after the page node are invalid physical page node, using physics
Page overriding technical security deletes data in invalid physical page；
Page node unit is deleted, for the GUID according to removal request, deletes all pages of knots in corresponding GUID-page table
Point, and head node is reinitialized；
The effective Physical Page unit of safety deleting, for the logical address of removal request and size to be resolved to multiple logical page (LPAGE)s
Number, address mapping table is searched according to logical page number (LPN), finds corresponding effective physical page number, technical security is override using Physical Page
Delete data in effective Physical Page；
Address of cache table unit is updated, for the effective Physical Page found to be set to invalid physical page, address is updated and reflects
Firing table.
In general, through the invention it is contemplated above technical scheme is compared with the prior art, have following technology special
Sign and the utility model has the advantages that
(1) safety deleting for the block grade granularity that compares, the present invention can be reduced safety deleting to the shadow of solid-state disk readwrite performance
It rings, does not need actual time safety and delete the invalid page that each file is generated by modification, only just need to hold when user deletes file
Row safety deleting；
(2) the more existing safety deleting method based on MLC is compared, the present invention is more efficient to the safety deleting of MLC flash, solution
Determined safety deleting MLC when programming interference the problem of, on the basis of safety deleting MLC, reduce the wave to MLC physical capacity
Take；
Detailed description of the invention
Fig. 1 is MLC Flash cell write sequence schematic diagram；
Fig. 2 is the implementation flow chart of the method for the present invention；
Fig. 3 is the structural schematic diagram of GUID_page table；
Fig. 4 is the flow chart of GUID distribution and encapsulation；
Fig. 5 is the flow chart for distributing the pairs of page of MLC flash；
Fig. 6 is the flow chart for recording the invalid page of file；
Fig. 7 is the flow chart of the safety deleting of SLC Flash；
Fig. 8 is the flow chart of the safety deleting of MLC flash；
Fig. 9 is the flow chart of metadata safety deleting.
Specific embodiment
In order to make the objectives, technical solutions, and advantages of the present invention clearer, with reference to the accompanying drawings and embodiments, right
The present invention is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, and
It is not used in the restriction present invention.As long as in addition, technical characteristic involved in the various embodiments of the present invention described below
Not constituting a conflict with each other can be combined with each other.
As shown in Fig. 2, the method for the present invention the following steps are included:
(1) GUID distribution and encapsulation: a globally unique identifier GUID is distributed for each file, and by the GUID of file
Be encapsulated into file write in removal request；If write request, then (2) are entered step；If removal request then enters step
(5)；
(2) write-in medium judges: if storage medium is MLC flash, entering step (3)；Otherwise (4) are entered step；
(3) it distributes the pairs of page of MLC flash: finding the Physical Page position of this document last time write-in according to write request No. GUID
It sets, if low page, then distributes the corresponding high page of the low page to write request, the data block of file is made to be distributed in the pairs of physics of MLC
In page；If high page, then idle low page is distributed to write request；If distributing the free time after starting garbage reclamation without free space
Low page is to write request；
(4) it records the invalid page of file: recording the invalid physical that each file generates in real time using GUID-page table
Page；
(5) deletion medium judges: if storage medium is MLC flash, entering step (6)；If storage medium is SLC sudden strain of a muscle
It deposits, then enters step (7)；
(6) based on the safety deleting of MLC flash: it is corresponding to find file to be deleted according to GUID-page table and removal request
All Physical Page, the use overriding technology progress safety deleting of the not super upper limit of overriding number of physical block where Physical Page covers
It writes and physical block erasing is reached into safety deleting after the active page in the migration physical block of the super upper limit of number；
(7) based on the safety deleting of SLC Flash: finding the file pair to be deleted according to GUID-page table and removal request
All Physical Page answered reuse Physical Page overriding technology and carry out safety deleting to data in these Physical Page；
(8) safety deleting of metadata: the metadata modification request and mapping relations generated according to file delete operation
Modification, finds the Physical Page where metadata, carries out safety deleting to Physical Page where metadata.
As shown in figure 3, GUID-page table structure described in the technical program are as follows:
The head node of each GUID-page table includes the pointer of No. GUID and one direction page node, each page node packet
It includes physical page number and is directed toward the pointer of next page node；Be directed toward in addition to head node first of the GUID-page table of MLC flash
Page node is effective page node, and in addition to this other page nodes are invalid page node；In the GUID-page table of SLC Flash
Page node is invalid page node.
It is illustrated in figure 4 the distribution and encapsulation process of GUID, due to the strange land renewing speciality of solid-state disk, the number of each file
May be in solid-state disk there are many invalid page copies according to block, existing file system does not know the invalid page copy of file hard
Storage location in part, therefore the technical program increases the distribution and encapsulation process of GUID in file system layer, gives each file
It distributes a GUID and carrys out each file of unique identification, and the GUID of this document is encapsulated into the write request or removal request of this document
In, the write request comprising GUID or removal request are passed into generic block layer, then be transmitted to driving layer, then be transmitted to mechanical floor,
Equipment is set to grasp the storage location of file data blocks by GUID.
In existing system, file system only deletes the metadata of file, does not delete when deleting file
Except the data block of file.For the safety deleting for realizing single file, need to open Trim function.The i.e. described removal request is Trim
Order, when user deletes file, operating system will send Trim instruction and will delete after file system receives Trim instruction
The GUID of the file removed is packaged into Trim request, is transmitted to generic block layer, then be transmitted to driving layer, then be transmitted to mechanical floor,
Which Physical Page of notification controller can be set in vain.
The transmission and transmission that operating system, file system, driving layer support Trim to instruct in the technical program embodiment,
Mechanical floor also supports the processing of Trim order.
When deleting certain file, the corresponding invalid page copy of this document can be searched by the GUID of removal request, and lead to
Cross the corresponding active page of data segment search this document of removal request；Specific embodiment process is as follows:
(11) the index node inode number that will execute the file write or deleted is recorded as the GUID of file；
(12) by the GUID of file be encapsulated into file write in removal request.
It is illustrated in figure 5 the distribution pairs of page process of MLC flash, since MLC flash chip has strict demand to write sequence,
It must first be write as to the low page in page, then be write as to the high page in page, otherwise will cause error in data；And exist between page in pairs
Programming interference, when overriding some page in pairs of page, mistake, therefore base occur for the data that will lead to another page in pairs of page
Difficult to realize in the safety deleting of MLC flash, the technical program is using a kind of completely new Physical Page method of salary distribution i.e. distribution in pairs
Mode, detailed process are as follows:
(31) Physical Page is inquired: being searched GUID-page table according to the GUID of write request, is found in corresponding GUID-page table
The physical page number for the page node that head node pointer is directed toward；
(32) page is judged: judges that the physical page number is low page, high page or physical page number initial value, if low page,
The corresponding high page of the low page is distributed to write request, enters step (35)；If high page or physical page number initial value, then judge
Whether available free low page if so, then distributing idle low page to write request enters step (34) in solid-state disk；Otherwise it enters step
(33)；
(33) garbage reclamation: the active page in the object block to be recycled first is migrated, while according to the corresponding GUID of active page
The physical page number for the page node that head node pointer is directed toward in corresponding GUID-page table is searched, if the physical page number of page node and having
The physical page number for imitating page is identical, then the physical page number of page node is changed to the physical page number after effective page migration；Otherwise it does not do and locates
Reason；Corresponding GUID-page table is searched according to the corresponding GUID of invalid page in object block later, deletes page knot in GUID-page table
The physical page number of point is equal to the page node of invalid page physical page number；Object block is wiped, the idle low page of distribution later is to write request；
(34) physical page number is updated: the physics for the page node that head node pointer in the GUID-page table of write request is directed toward
Page number is updated to newly distribute the physical page number of Physical Page.
The advantage of doing so is that can be override the corresponding high and low page of file together when carrying out safety deleting to file,
Avoid programming interference bring error in data problem when overriding MLC between pairs of page.
The invalid page process for being illustrated in figure 6 record file not only needs to realize the safety deleting of flash file grade
Corresponding active page of the safety deleting file in solid-state disk, it is also necessary to the invalid page pair that safety deleting file is generated by modification
This；The invalid physical page and effective Physical Page generated therefore, it is necessary to record each file in real time；Wherein file is corresponding effectively
Physical Page can be found by delete command, i.e., when user deletes file, mechanical floor is by the data of the delete command received
Section is parsed into multiple logical page number (LPN)s, obtains the corresponding effective physical page number of file by searching for address mapping table；But due to mapping
The one-to-one relationship of table cannot find the corresponding invalid physical page of file by logical page number (LPN)；Therefore a kind of scheme is needed
Record the corresponding invalid physical page of file；Detailed process is as follows:
(41) it writes hit judgement: address mapping table is searched according to the logical address of write request, if hit, enters step
(42)；Otherwise (43) are entered step；
(42) it records invalid physical page: the state of old physical page is set to the page knot for distributing new GUID-page table in vain
The physical page number of point, page node is the old physical page number, and new page node is linked at the corresponding GUID-page of GUID of write request
Table tail portion；
(43) it updates address mapping table: updating address mapping table.
It is illustrated in figure 7 the process of the safety deleting of SLC Flash, SLC Flash on the market all supports covering substantially at present
It is written (" 1 " can only be changed to " 0 "), (i.e. second of write operation) can be override to Physical Page before erasing, and to flash memory
Error rate do not generate apparent influence；Therefore, for SLC Flash, the technical program records each file in real time and is editing
This document is found by the GUID and data segment of delete command when deleting file with the invalid physical page generated during modification
Corresponding all effective Physical Page and invalid physical page, reuse Physical Page overwrite method and override to these Physical Page, from
And realize the file-level safety deleting of SLC Flash；Detailed process is as follows:
(71) safety deleting invalid physical page: according to the GUID of removal request, the head knot in corresponding GUID-page table is searched
The page node that pointer is directed toward is put, all page nodes linked after the page node are invalid physical page node, are covered using Physical Page
Data in writing technology safety deleting invalid physical page；
(72) it deletes page node: according to the GUID of removal request, deleting all page nodes in corresponding GUID-page table, and
Head node is reinitialized；
(73) the effective Physical Page of safety deleting: resolving to multiple logical page number (LPN)s for the logical address of removal request and size,
Address mapping table is searched according to logical page number (LPN), finds corresponding effective physical page number, is deleted using Physical Page overriding technical security
Except data in effective Physical Page；
(74) it updates address mapping table: the effective Physical Page found being set to invalid physical page, updates address mapping table.
If Fig. 8 is the process of the safety deleting of MLC flash, when the technical program carries out the safety deleting deleted based on MLC,
The corresponding all effective Physical Page of this document and invalid physical page are found by, the GUID of delete command and data segment, is pacified simultaneously
It is complete to delete file corresponding high page and low page in MLC flash, avoid the influence of programming interference；Pass through the every of test MLC flash
The overriding number of pages that a block can be born, setting overriding threshold value, when the number of pages that some block is written in MLC flash has been more than overriding threshold value
When, it does not use Physical Page overwrite method and carries out safety deleting, but the active page in the block is migrated, which is wiped to reach
The purpose of safety deleting；Detailed process is as follows:
(61) search invalid physical page: according to the GUID of removal request, the head node searched in corresponding GUID-page table refers to
The page node that needle is directed toward, all page nodes linked after the page node are invalid physical page node；
(62) it resets GUID-page table: according to the GUID of removal request, deleting all pages of knots in corresponding GUID-page table
Point, and head node is reinitialized；
(63) it searches effective Physical Page: the logical address of removal request and size is resolved into multiple logical page number (LPN)s, according to
Logical page number (LPN) searches address mapping table, finds corresponding effective physical page number, the state of the effective Physical Page found is set to nothing
Effect；
(64) overriding number judgement: for all Physical Page found, the overriding of physical block is counted where judging Physical Page
Whether be more than the physical block overriding maximum number of times；If being not above, (65) are entered step；Otherwise (66) are entered step；
(65) overriding is deleted: using data in Physical Page overriding technical security deletion of physically page；Physics where the Physical Page
Count is incremented for the overriding of block；
(66) physical block is wiped: migrating all effective Physical Page in the physical block where the Physical Page, while more cenotype
Address mapping table and GUID-page table are answered, the physical block is wiped later and realizes safety deleting.
If Fig. 9 is the process of metadata safety deleting, after the data block safety deleting of file, the metadata information of file
The title of such as file, inode node, map information metadata still residual in a flash memory, can reveal the file information.Therefore,
It needs further to carry out safety deleting to the relevant metadata of this document, thoroughly to eliminate trace；Detailed process is as follows:
(81) modification of metadata the modification request and mapping relations generated according to file delete operation, finds metadata institute
Physical Page；
(82) Physical Page is judged whether by safety deleting mistake, if so, terminating to delete；Otherwise to where metadata
Physical Page carries out safety deleting, i.e., overrides the data in these Physical Page using Physical Page overriding technology, and indicate the page
By safety deleting.
As it will be easily appreciated by one skilled in the art that the foregoing is merely illustrative of the preferred embodiments of the present invention, not to
The limitation present invention, any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should all include
Within protection scope of the present invention.
Claims (8)
1. a kind of flash memory safety deleting method based on file-level granularity, which is characterized in that the method specifically includes:
(1) GUID distribution and encapsulation: a globally unique identifier GUID is distributed for each file, and the GUID of file is encapsulated
To file write in removal request；If write request, then (2) are entered step；If removal request then enters step (5)；
(2) write-in medium judges: if storage medium is MLC flash, entering step (3)；Otherwise (4) are entered step；
(3) it distributes the pairs of page of MLC flash: finding the physical page locations of this document last time write-in according to write request No. GUID,
If low page, then the corresponding high page of the low page is distributed to write request, the data block of file is made to be distributed in the pairs of Physical Page of MLC
In；If high page, then idle low page is distributed to write request；If distribution is idle low after starting garbage reclamation without idle low page
Page gives write request；
(4) it records the invalid page of file: recording the invalid physical page that each file generates in real time using GUID-page table；
(5) deletion medium judges: if storage medium is MLC flash, entering step (6)；If storage medium is SLC Flash,
Enter step (7)；
(6) based on the safety deleting of MLC flash: finding the corresponding institute of file to be deleted according to GUID-page table and removal request
There is Physical Page, the not super upper limit of overriding number of physical block where Physical Page carries out safety deleting, overriding time using overriding technology
Physical block erasing is reached into safety deleting after active page in the migration physical block of the super upper limit of number；
The step (6) specifically includes:
(61) search invalid physical page: according to the GUID of removal request, the head node pointer searched in corresponding GUID-page table refers to
To page node, all page nodes linked after the page node are invalid physical page node；
(62) it resets GUID-page table: according to the GUID of removal request, deleting all page nodes in corresponding GUID-page table, and
Head node is reinitialized；
(63) it searches effective Physical Page: the logical address of removal request and size being resolved into multiple logical page number (LPN)s, according to logic
Page number lookup address mapping table finds corresponding effective physical page number, and the state of the effective Physical Page found is set in vain；
(64) overriding number judgement: for all Physical Page found, whether the overriding counting of physical block where judging Physical Page
More than the overriding maximum number of times of the physical block；If being not above, (65) are entered step；Otherwise (66) are entered step；
(65) overriding is deleted: using data in Physical Page overriding technical security deletion of physically page；Physical block where the Physical Page
Count is incremented for overriding；
(66) physical block is wiped: being migrated all effective Physical Page in the physical block where the Physical Page, while being updated correspondingly
Location mapping table and GUID-page table wipe the physical block later and realize safety deleting；(7) based on the safety deleting of SLC Flash:
The corresponding all Physical Page of the file to be deleted are found according to GUID-page table and removal request, reuse Physical Page overriding skill
Art carries out safety deleting to data in these Physical Page；
(8) safety deleting of metadata: the metadata modification generated according to file delete operation is requested and the modification of mapping relations,
The Physical Page where metadata is found, safety deleting is carried out to Physical Page where metadata.
2. a kind of flash memory safety deleting method based on file-level granularity according to claim 1, which is characterized in that described
Step (3) specifically includes:
(31) Physical Page is inquired: being searched GUID-page table according to the GUID of write request, is found head knot in corresponding GUID-page table
The physical page number for the page node that point pointer is directed toward；
(32) page is judged: judges that the physical page number is low page, high page or physical page number initial value, if low page, distribution
The corresponding high page of the low page enters step (35) to write request；If high page or physical page number initial value, then judge solid-state
Whether available free low page if so, then distributing idle low page to write request enters step (34) in disk；Otherwise (33) are entered step；
(33) garbage reclamation: the active page in the object block to be recycled first is migrated, while being searched according to the corresponding GUID of active page
The physical page number for the page node that head node pointer is directed toward in corresponding GUID-page table, if the physical page number and active page of page node
Physical page number it is identical, then the physical page number of page node is changed to the physical page number after effective page migration；Otherwise it is not processed；It
Corresponding GUID-page table is searched according to the corresponding GUID of invalid page in object block afterwards, deletes the object of page node in GUID-page table
Manage the page node that page number is equal to invalid page physical page number；Object block is wiped, the idle low page of distribution later is to write request；
(34) physical page number is updated: the physical page number for the page node that head node pointer in the GUID-page table of write request is directed toward
It is updated to newly distribute the physical page number of Physical Page.
3. a kind of flash memory safety deleting method based on file-level granularity according to claim 1, which is characterized in that described
Step (4) specifically includes:
(41) it writes hit judgement: address mapping table is searched according to the logical address of write request, if hit, enters step (42)；
Otherwise (43) are entered step；
(42) it records invalid physical page: the state of old physical page is set to the page node for distributing new GUID-page table in vain,
The physical page number of page node is the page number of the old physical page, and new page node is linked at the corresponding GUID- of GUID of write request
Page table tail portion；
(43) it updates address mapping table: updating address mapping table.
4. a kind of flash memory safety deleting method based on file-level granularity according to claim 1, which is characterized in that described
Step (7) specifically includes:
(71) safety deleting invalid physical page: according to the GUID of removal request, the head node searched in corresponding GUID-page table refers to
The page node that needle is directed toward, all page nodes linked after the page node are invalid physical page node, override skill using Physical Page
Data in art safety deleting invalid physical page；
(72) it deletes page node: according to the GUID of removal request, deleting all page nodes in corresponding GUID-page table, and by head
Node reinitializes；
(73) the effective Physical Page of safety deleting: resolving to multiple logical page number (LPN)s for the logical address of removal request and size, according to
Logical page number (LPN) searches address mapping table, finds corresponding effective physical page number, is had using Physical Page overriding technical security deletion
Imitate data in Physical Page；
(74) it updates address mapping table: the effective Physical Page found being set to invalid physical page, updates address mapping table.
5. a kind of flash memory safety deleting system based on file-level granularity, which is characterized in that the system specifically includes:
GUID distribution and package module, for distributing a globally unique identifier GUID for each file, and by file
GUID be encapsulated into file write in removal request；If write request, then enter write-in medium judgment module；If removal request
Then enter and deletes medium judgment module；
Medium judgment module is written, if for judging that storage medium as MLC flash, enters the pairs of page distribution module of MLC flash；
Otherwise enter file is invalid page logging modle；
The pairs of page distribution module of MLC flash, for finding the Physical Page of this document last time write-in according to No. GUID of write request
Position then distributes the corresponding high page of the low page to write request, the data block of file is made to be distributed in the pairs of object of MLC if low page
It manages in page；If high page, then idle low page is distributed to write request；If distributing sky after starting garbage reclamation without free space
Not busy low page is to write request；
Page logging modle that file is invalid, for recording the invalid physical page that each file generates in real time using GUID-page table；
Medium judgment module is deleted, if for judging that storage medium as MLC flash, enters the safety deleting based on MLC flash
Module；If storage medium is SLC Flash, enter the safety deleting module based on SLC Flash；
Safety deleting module based on MLC flash, it is corresponding for finding file to be deleted according to GUID-page table and removal request
All Physical Page, the use overriding technology progress safety deleting of the not super upper limit of overriding number of physical block where Physical Page covers
It writes and physical block erasing is reached into safety deleting after the active page in the migration physical block of the super upper limit of number；
The safety deleting module based on MLC flash specifically includes:
Invalid physical page unit is searched, for the GUID according to removal request, the head node searched in corresponding GUID-page table refers to
The page node that needle is directed toward, all page nodes linked after the page node are invalid physical page node；
GUID-page table unit is reset, for the GUID according to removal request, deletes all pages of knots in corresponding GUID-page table
Point, and head node is reinitialized；
Effective Physical Page unit is searched, for the logical address of removal request and size to be resolved to multiple logical page number (LPN)s, according to
Logical page number (LPN) searches address mapping table, finds corresponding effective physical page number, the state of the effective Physical Page found is set to nothing
Effect；
Frequency judging unit is override, for for all Physical Page found, the overriding of physical block to be counted where judging Physical Page
Whether be more than the physical block overriding maximum number of times；If being not above, enters overriding and delete unit；Otherwise enter physical block to wipe
Except unit；
Unit is deleted in overriding, for using data in Physical Page overriding technical security deletion of physically page；Physics where the Physical Page
Count is incremented for the overriding of block；
Physical block wipes unit, for migrating all effective Physical Page in the physical block where the Physical Page, while more cenotype
Address mapping table and GUID-page table are answered, the physical block is wiped later and realizes safety deleting；
Safety deleting module based on SLC Flash, for finding the file pair to be deleted according to GUID-page table and removal request
All Physical Page answered reuse Physical Page overriding technology and carry out safety deleting to data in these Physical Page；
The safety deleting module of metadata, metadata modification request and mapping relations for being generated according to file delete operation
Modification, finds the Physical Page where metadata, carries out safety deleting to Physical Page where metadata.
6. a kind of flash memory safety deleting system based on file-level granularity according to claim 5, which is characterized in that described
The pairs of page distribution module of MLC flash specifically includes:
Physical Page query unit is found in corresponding GUID-page table for searching GUID-page table according to the GUID of write request
The physical page number for the page node that head node pointer is directed toward；
To page judging unit, for judging that the physical page number is low page, high page or physical page number initial value, if low page,
The corresponding high page of the low page is distributed to write request, into update physical page number unit；If high page or physical page number are initial
Value, then judge in solid-state disk whether available free low page, if so, then distribute idle low page to write request, into updating physical page number
Unit；Otherwise enter garbage reclamation unit；
Garbage reclamation unit: for first migrating the active page in the object block to be recycled, while according to the corresponding GUID of active page
The physical page number for the page node that head node pointer is directed toward in corresponding GUID-page table is searched, if the physical page number of page node and having
The physical page number for imitating page is identical, then the physical page number of page node is changed to the physical page number after effective page migration；Otherwise it does not do and locates
Reason；Corresponding GUID-page table is searched according to the corresponding GUID of invalid page in object block later, deletes page knot in GUID-page table
The physical page number of point is equal to the page node of invalid page physical page number；Object block is wiped, the idle low page of distribution later is to write request；
Physical page number unit is updated, the physics for the page node that head node pointer in the GUID-page table by write request is directed toward
Page number is updated to newly distribute the physical page number of Physical Page.
7. a kind of flash memory safety deleting system based on file-level granularity according to claim 5, which is characterized in that described
File is invalid, and page logging modle specifically includes:
Hit judging unit is write, for searching address mapping table according to the logical address of write request, if hit, enters record nothing
Imitate Physical Page unit；Otherwise enter and update address of cache table unit；
Invalid physical page unit is recorded, for the state of old physical page to be set to the page knot for distributing new GUID-page table in vain
Point, the physical page number of page node are the page number of the old physical page, and new page node is linked at the corresponding GUID- of GUID of write request
Page table tail portion；
Address of cache table unit is updated, for updating address mapping table.
8. a kind of flash memory safety deleting system based on file-level granularity according to claim 5, which is characterized in that described
Safety deleting module based on SLC Flash specifically includes:
Safety deleting invalid physical page unit searches the head knot in corresponding GUID-page table for the GUID according to removal request
The page node that pointer is directed toward is put, all page nodes linked after the page node are invalid physical page node, are covered using Physical Page
Data in writing technology safety deleting invalid physical page；
Page node unit is deleted, for the GUID according to removal request, deletes all page nodes in corresponding GUID-page table, and
Head node is reinitialized；
The effective Physical Page unit of safety deleting, for the logical address of removal request and size to be resolved to multiple logical page number (LPN)s,
Address mapping table is searched according to logical page number (LPN), finds corresponding effective physical page number, is deleted using Physical Page overriding technical security
Except data in effective Physical Page；
Address of cache table unit is updated, for the effective Physical Page found to be set to invalid physical page, updates address mapping table.
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| CN1700341A (en) * | 2004-05-18 | 2005-11-23 | 三星电子株式会社 | Method, medium, and apparatus for deleting data and method, medium, and apparatus for restoring deletion data |
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