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linux-stable/fs/xfs/libxfs/xfs_bmap.h
Darrick J. Wong 00fd1d56dd xfs: redesign the reflink remap loop to fix blkres depletion crash 
The existing reflink remapping loop has some structural problems that
need addressing:

The biggest problem is that we create one transaction for each extent in
the source file without accounting for the number of mappings there are
for the same range in the destination file.  In other words, we don't
know the number of remap operations that will be necessary and we
therefore cannot guess the block reservation required.  On highly
fragmented filesystems (e.g. ones with active dedupe) we guess wrong,
run out of block reservation, and fail.

The second problem is that we don't actually use the bmap intents to
their full potential -- instead of calling bunmapi directly and having
to deal with its backwards operation, we could call the deferred ops
xfs_bmap_unmap_extent and xfs_refcount_decrease_extent instead.  This
makes the frontend loop much simpler.

Solve all of these problems by refactoring the remapping loops so that
we only perform one remapping operation per transaction, and each
operation only tries to remap a single extent from source to dest.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reported-by: Edwin Török <edwin@etorok.net>
Tested-by: Edwin Török <edwin@etorok.net>
2020-07-06 10:46:57 -07:00

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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (c) 2000-2006 Silicon Graphics, Inc.
* All Rights Reserved.
*/
#ifndef __XFS_BMAP_H__
#define __XFS_BMAP_H__
struct getbmap;
struct xfs_bmbt_irec;
struct xfs_ifork;
struct xfs_inode;
struct xfs_mount;
struct xfs_trans;
extern kmem_zone_t *xfs_bmap_free_item_zone;
/*
* Argument structure for xfs_bmap_alloc.
*/
struct xfs_bmalloca {
struct xfs_trans *tp; /* transaction pointer */
struct xfs_inode *ip; /* incore inode pointer */
struct xfs_bmbt_irec prev; /* extent before the new one */
struct xfs_bmbt_irec got; /* extent after, or delayed */
xfs_fileoff_t offset; /* offset in file filling in */
xfs_extlen_t length; /* i/o length asked/allocated */
xfs_fsblock_t blkno; /* starting block of new extent */
struct xfs_btree_cur *cur; /* btree cursor */
struct xfs_iext_cursor icur; /* incore extent cursor */
int nallocs;/* number of extents alloc'd */
int logflags;/* flags for transaction logging */
xfs_extlen_t total; /* total blocks needed for xaction */
xfs_extlen_t minlen; /* minimum allocation size (blocks) */
xfs_extlen_t minleft; /* amount must be left after alloc */
bool eof; /* set if allocating past last extent */
bool wasdel; /* replacing a delayed allocation */
bool aeof; /* allocated space at eof */
bool conv; /* overwriting unwritten extents */
int datatype;/* data type being allocated */
int flags;
};
/*
* List of extents to be free "later".
* The list is kept sorted on xbf_startblock.
*/
struct xfs_extent_free_item
{
xfs_fsblock_t xefi_startblock;/* starting fs block number */
xfs_extlen_t xefi_blockcount;/* number of blocks in extent */
struct list_head xefi_list;
struct xfs_owner_info xefi_oinfo; /* extent owner */
bool xefi_skip_discard;
};
#define XFS_BMAP_MAX_NMAP 4
/*
* Flags for xfs_bmapi_*
*/
#define XFS_BMAPI_ENTIRE 0x001 /* return entire extent, not trimmed */
#define XFS_BMAPI_METADATA 0x002 /* mapping metadata not user data */
#define XFS_BMAPI_ATTRFORK 0x004 /* use attribute fork not data */
#define XFS_BMAPI_PREALLOC 0x008 /* preallocation op: unwritten space */
#define XFS_BMAPI_CONTIG 0x020 /* must allocate only one extent */
/*
* unwritten extent conversion - this needs write cache flushing and no additional
* allocation alignments. When specified with XFS_BMAPI_PREALLOC it converts
* from written to unwritten, otherwise convert from unwritten to written.
*/
#define XFS_BMAPI_CONVERT 0x040
/*
* allocate zeroed extents - this requires all newly allocated user data extents
* to be initialised to zero. It will be ignored if XFS_BMAPI_METADATA is set.
* Use in conjunction with XFS_BMAPI_CONVERT to convert unwritten extents found
* during the allocation range to zeroed written extents.
*/
#define XFS_BMAPI_ZERO 0x080
/*
* Map the inode offset to the block given in ap->firstblock. Primarily
* used for reflink. The range must be in a hole, and this flag cannot be
* turned on with PREALLOC or CONVERT, and cannot be used on the attr fork.
*
* For bunmapi, this flag unmaps the range without adjusting quota, reducing
* refcount, or freeing the blocks.
*/
#define XFS_BMAPI_REMAP 0x100
/* Map something in the CoW fork. */
#define XFS_BMAPI_COWFORK 0x200
/* Skip online discard of freed extents */
#define XFS_BMAPI_NODISCARD 0x1000
/* Do not update the rmap btree. Used for reconstructing bmbt from rmapbt. */
#define XFS_BMAPI_NORMAP 0x2000
#define XFS_BMAPI_FLAGS \
{ XFS_BMAPI_ENTIRE, "ENTIRE" }, \
{ XFS_BMAPI_METADATA, "METADATA" }, \
{ XFS_BMAPI_ATTRFORK, "ATTRFORK" }, \
{ XFS_BMAPI_PREALLOC, "PREALLOC" }, \
{ XFS_BMAPI_CONTIG, "CONTIG" }, \
{ XFS_BMAPI_CONVERT, "CONVERT" }, \
{ XFS_BMAPI_ZERO, "ZERO" }, \
{ XFS_BMAPI_REMAP, "REMAP" }, \
{ XFS_BMAPI_COWFORK, "COWFORK" }, \
{ XFS_BMAPI_NODISCARD, "NODISCARD" }, \
{ XFS_BMAPI_NORMAP, "NORMAP" }
static inline int xfs_bmapi_aflag(int w)
{
return (w == XFS_ATTR_FORK ? XFS_BMAPI_ATTRFORK :
(w == XFS_COW_FORK ? XFS_BMAPI_COWFORK : 0));
}
static inline int xfs_bmapi_whichfork(int bmapi_flags)
{
if (bmapi_flags & XFS_BMAPI_COWFORK)
return XFS_COW_FORK;
else if (bmapi_flags & XFS_BMAPI_ATTRFORK)
return XFS_ATTR_FORK;
return XFS_DATA_FORK;
}
/*
* Special values for xfs_bmbt_irec_t br_startblock field.
*/
#define DELAYSTARTBLOCK ((xfs_fsblock_t)-1LL)
#define HOLESTARTBLOCK ((xfs_fsblock_t)-2LL)
/*
* Flags for xfs_bmap_add_extent*.
*/
#define BMAP_LEFT_CONTIG (1 << 0)
#define BMAP_RIGHT_CONTIG (1 << 1)
#define BMAP_LEFT_FILLING (1 << 2)
#define BMAP_RIGHT_FILLING (1 << 3)
#define BMAP_LEFT_DELAY (1 << 4)
#define BMAP_RIGHT_DELAY (1 << 5)
#define BMAP_LEFT_VALID (1 << 6)
#define BMAP_RIGHT_VALID (1 << 7)
#define BMAP_ATTRFORK (1 << 8)
#define BMAP_COWFORK (1 << 9)
#define XFS_BMAP_EXT_FLAGS \
{ BMAP_LEFT_CONTIG, "LC" }, \
{ BMAP_RIGHT_CONTIG, "RC" }, \
{ BMAP_LEFT_FILLING, "LF" }, \
{ BMAP_RIGHT_FILLING, "RF" }, \
{ BMAP_ATTRFORK, "ATTR" }, \
{ BMAP_COWFORK, "COW" }
/* Return true if the extent is an allocated extent, written or not. */
static inline bool xfs_bmap_is_real_extent(struct xfs_bmbt_irec *irec)
{
return irec->br_startblock != HOLESTARTBLOCK &&
irec->br_startblock != DELAYSTARTBLOCK &&
!isnullstartblock(irec->br_startblock);
}
/*
* Return true if the extent is a real, allocated extent, or false if it is a
* delayed allocation, and unwritten extent or a hole.
*/
static inline bool xfs_bmap_is_written_extent(struct xfs_bmbt_irec *irec)
{
return xfs_bmap_is_real_extent(irec) &&
irec->br_state != XFS_EXT_UNWRITTEN;
}
/*
* Check the mapping for obviously garbage allocations that could trash the
* filesystem immediately.
*/
#define xfs_valid_startblock(ip, startblock) \
((startblock) != 0 || XFS_IS_REALTIME_INODE(ip))
void xfs_trim_extent(struct xfs_bmbt_irec *irec, xfs_fileoff_t bno,
xfs_filblks_t len);
int xfs_bmap_add_attrfork(struct xfs_inode *ip, int size, int rsvd);
int xfs_bmap_set_attrforkoff(struct xfs_inode *ip, int size, int *version);
void xfs_bmap_local_to_extents_empty(struct xfs_trans *tp,
struct xfs_inode *ip, int whichfork);
void __xfs_bmap_add_free(struct xfs_trans *tp, xfs_fsblock_t bno,
xfs_filblks_t len, const struct xfs_owner_info *oinfo,
bool skip_discard);
void xfs_bmap_compute_maxlevels(struct xfs_mount *mp, int whichfork);
int xfs_bmap_first_unused(struct xfs_trans *tp, struct xfs_inode *ip,
xfs_extlen_t len, xfs_fileoff_t *unused, int whichfork);
int xfs_bmap_last_before(struct xfs_trans *tp, struct xfs_inode *ip,
xfs_fileoff_t *last_block, int whichfork);
int xfs_bmap_last_offset(struct xfs_inode *ip, xfs_fileoff_t *unused,
int whichfork);
int xfs_bmap_one_block(struct xfs_inode *ip, int whichfork);
int xfs_bmapi_read(struct xfs_inode *ip, xfs_fileoff_t bno,
xfs_filblks_t len, struct xfs_bmbt_irec *mval,
int *nmap, int flags);
int xfs_bmapi_write(struct xfs_trans *tp, struct xfs_inode *ip,
xfs_fileoff_t bno, xfs_filblks_t len, int flags,
xfs_extlen_t total, struct xfs_bmbt_irec *mval, int *nmap);
int __xfs_bunmapi(struct xfs_trans *tp, struct xfs_inode *ip,
xfs_fileoff_t bno, xfs_filblks_t *rlen, int flags,
xfs_extnum_t nexts);
int xfs_bunmapi(struct xfs_trans *tp, struct xfs_inode *ip,
xfs_fileoff_t bno, xfs_filblks_t len, int flags,
xfs_extnum_t nexts, int *done);
int xfs_bmap_del_extent_delay(struct xfs_inode *ip, int whichfork,
struct xfs_iext_cursor *cur, struct xfs_bmbt_irec *got,
struct xfs_bmbt_irec *del);
void xfs_bmap_del_extent_cow(struct xfs_inode *ip,
struct xfs_iext_cursor *cur, struct xfs_bmbt_irec *got,
struct xfs_bmbt_irec *del);
uint xfs_default_attroffset(struct xfs_inode *ip);
int xfs_bmap_collapse_extents(struct xfs_trans *tp, struct xfs_inode *ip,
xfs_fileoff_t *next_fsb, xfs_fileoff_t offset_shift_fsb,
bool *done);
int xfs_bmap_can_insert_extents(struct xfs_inode *ip, xfs_fileoff_t off,
xfs_fileoff_t shift);
int xfs_bmap_insert_extents(struct xfs_trans *tp, struct xfs_inode *ip,
xfs_fileoff_t *next_fsb, xfs_fileoff_t offset_shift_fsb,
bool *done, xfs_fileoff_t stop_fsb);
int xfs_bmap_split_extent(struct xfs_trans *tp, struct xfs_inode *ip,
xfs_fileoff_t split_offset);
int xfs_bmapi_reserve_delalloc(struct xfs_inode *ip, int whichfork,
xfs_fileoff_t off, xfs_filblks_t len, xfs_filblks_t prealloc,
struct xfs_bmbt_irec *got, struct xfs_iext_cursor *cur,
int eof);
int xfs_bmapi_convert_delalloc(struct xfs_inode *ip, int whichfork,
xfs_off_t offset, struct iomap *iomap, unsigned int *seq);
int xfs_bmap_add_extent_unwritten_real(struct xfs_trans *tp,
struct xfs_inode *ip, int whichfork,
struct xfs_iext_cursor *icur, struct xfs_btree_cur **curp,
struct xfs_bmbt_irec *new, int *logflagsp);
static inline void
xfs_bmap_add_free(
struct xfs_trans *tp,
xfs_fsblock_t bno,
xfs_filblks_t len,
const struct xfs_owner_info *oinfo)
{
__xfs_bmap_add_free(tp, bno, len, oinfo, false);
}
enum xfs_bmap_intent_type {
XFS_BMAP_MAP = 1,
XFS_BMAP_UNMAP,
};
struct xfs_bmap_intent {
struct list_head bi_list;
enum xfs_bmap_intent_type bi_type;
struct xfs_inode *bi_owner;
int bi_whichfork;
struct xfs_bmbt_irec bi_bmap;
};
int xfs_bmap_finish_one(struct xfs_trans *tp, struct xfs_inode *ip,
enum xfs_bmap_intent_type type, int whichfork,
xfs_fileoff_t startoff, xfs_fsblock_t startblock,
xfs_filblks_t *blockcount, xfs_exntst_t state);
void xfs_bmap_map_extent(struct xfs_trans *tp, struct xfs_inode *ip,
struct xfs_bmbt_irec *imap);
void xfs_bmap_unmap_extent(struct xfs_trans *tp, struct xfs_inode *ip,
struct xfs_bmbt_irec *imap);
static inline int xfs_bmap_fork_to_state(int whichfork)
{
switch (whichfork) {
case XFS_ATTR_FORK:
return BMAP_ATTRFORK;
case XFS_COW_FORK:
return BMAP_COWFORK;
default:
return 0;
}
}
xfs_failaddr_t xfs_bmap_validate_extent(struct xfs_inode *ip, int whichfork,
struct xfs_bmbt_irec *irec);
int xfs_bmapi_remap(struct xfs_trans *tp, struct xfs_inode *ip,
xfs_fileoff_t bno, xfs_filblks_t len, xfs_fsblock_t startblock,
int flags);
#endif /* __XFS_BMAP_H__ */
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