// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2017-2023 Oracle.  All Rights Reserved.
 * Author: Darrick J. Wong <djwong@kernel.org>
 */
#ifndef __XFS_SCRUB_SCRUB_H__
#define __XFS_SCRUB_SCRUB_H__

struct xfs_scrub;

struct xchk_relax {
        unsigned long   next_resched;
        unsigned int    resched_nr;
        bool            interruptible;
};

/* Yield to the scheduler at most 10x per second. */
#define XCHK_RELAX_NEXT         (jiffies + (HZ / 10))

#define INIT_XCHK_RELAX \
        (struct xchk_relax){ \
                .next_resched   = XCHK_RELAX_NEXT, \
                .resched_nr     = 0, \
                .interruptible  = true, \
        }

/*
 * Relax during a scrub operation and exit if there's a fatal signal pending.
 *
 * If preemption is disabled, we need to yield to the scheduler every now and
 * then so that we don't run afoul of the soft lockup watchdog or RCU stall
 * detector.  cond_resched calls are somewhat expensive (~5ns) so we want to
 * ratelimit this to 10x per second.  Amortize the cost of the other checks by
 * only doing it once every 100 calls.
 */
static inline int xchk_maybe_relax(struct xchk_relax *widget)
{
        /* Amortize the cost of scheduling and checking signals. */
        if (likely(++widget->resched_nr < 100))
                return 0;
        widget->resched_nr = 0;

        if (unlikely(widget->next_resched <= jiffies)) {
                cond_resched();
                widget->next_resched = XCHK_RELAX_NEXT;
        }

        if (widget->interruptible && fatal_signal_pending(current))
                return -EINTR;

        return 0;
}

/*
 * Standard flags for allocating memory within scrub.  NOFS context is
 * configured by the process allocation scope.  Scrub and repair must be able
 * to back out gracefully if there isn't enough memory.  Force-cast to avoid
 * complaints from static checkers.
 */
#define XCHK_GFP_FLAGS  ((__force gfp_t)(GFP_KERNEL | __GFP_NOWARN | \
                                         __GFP_RETRY_MAYFAIL))

/*
 * For opening files by handle for fsck operations, we don't trust the inumber
 * or the allocation state; therefore, perform an untrusted lookup.  We don't
 * want these inodes to pollute the cache, so mark them for immediate removal.
 */
#define XCHK_IGET_FLAGS (XFS_IGET_UNTRUSTED | XFS_IGET_DONTCACHE)

/* Type info and names for the scrub types. */
enum xchk_type {
        ST_NONE = 1,    /* disabled */
        ST_PERAG,       /* per-AG metadata */
        ST_FS,          /* per-FS metadata */
        ST_INODE,       /* per-inode metadata */
        ST_GENERIC,     /* determined by the scrubber */
        ST_RTGROUP,     /* rtgroup metadata */
};

struct xchk_meta_ops {
        /* Acquire whatever resources are needed for the operation. */
        int             (*setup)(struct xfs_scrub *sc);

        /* Examine metadata for errors. */
        int             (*scrub)(struct xfs_scrub *);

        /* Repair or optimize the metadata. */
        int             (*repair)(struct xfs_scrub *);

        /*
         * Re-scrub the metadata we repaired, in case there's extra work that
         * we need to do to check our repair work.  If this is NULL, we'll use
         * the ->scrub function pointer, assuming that the regular scrub is
         * sufficient.
         */
        int             (*repair_eval)(struct xfs_scrub *sc);

        /* Decide if we even have this piece of metadata. */
        bool            (*has)(const struct xfs_mount *);

        /* type describing required/allowed inputs */
        enum xchk_type  type;
};

/* Buffer pointers and btree cursors for an entire AG. */
struct xchk_ag {
        struct xfs_perag        *pag;

        /* AG btree roots */
        struct xfs_buf          *agf_bp;
        struct xfs_buf          *agi_bp;

        /* AG btrees */
        struct xfs_btree_cur    *bno_cur;
        struct xfs_btree_cur    *cnt_cur;
        struct xfs_btree_cur    *ino_cur;
        struct xfs_btree_cur    *fino_cur;
        struct xfs_btree_cur    *rmap_cur;
        struct xfs_btree_cur    *refc_cur;
};

/* Inode lock state for the RT volume. */
struct xchk_rt {
        /* incore rtgroup, if applicable */
        struct xfs_rtgroup      *rtg;

        /* XFS_RTGLOCK_* lock state if locked */
        unsigned int            rtlock_flags;

        /* rtgroup btrees */
        struct xfs_btree_cur    *rmap_cur;
        struct xfs_btree_cur    *refc_cur;
};

struct xfs_scrub {
        /* General scrub state. */
        struct xfs_mount                *mp;
        struct xfs_scrub_metadata       *sm;
        const struct xchk_meta_ops      *ops;
        struct xfs_trans                *tp;

        /* File that scrub was called with. */
        struct file                     *file;

        /*
         * File that is undergoing the scrub operation.  This can differ from
         * the file that scrub was called with if we're checking file-based fs
         * metadata (e.g. rt bitmaps) or if we're doing a scrub-by-handle for
         * something that can't be opened directly (e.g. symlinks).
         */
        struct xfs_inode                *ip;

        /* Kernel memory buffer used by scrubbers; freed at teardown. */
        void                            *buf;

        /*
         * Clean up resources owned by whatever is in the buffer.  Cleanup can
         * be deferred with this hook as a means for scrub functions to pass
         * data to repair functions.  This function must not free the buffer
         * itself.
         */
        void                            (*buf_cleanup)(void *buf);

        /* xfile used by the scrubbers; freed at teardown. */
        struct xfile                    *xfile;

        /* buffer target for in-memory btrees; also freed at teardown. */
        struct xfs_buftarg              *xmbtp;

        /* Lock flags for @ip. */
        uint                            ilock_flags;

        /* The orphanage, for stashing files that have lost their parent. */
        uint                            orphanage_ilock_flags;
        struct xfs_inode                *orphanage;

        /* A temporary file on this filesystem, for staging new metadata. */
        struct xfs_inode                *tempip;
        uint                            temp_ilock_flags;

        /* See the XCHK/XREP state flags below. */
        unsigned int                    flags;

        /*
         * The XFS_SICK_* flags that correspond to the metadata being scrubbed
         * or repaired.  We will use this mask to update the in-core fs health
         * status with whatever we find.
         */
        unsigned int                    sick_mask;

        /*
         * Clear these XFS_SICK_* flags but only if the scan is ok.  Useful for
         * removing ZAPPED flags after a repair.
         */
        unsigned int                    healthy_mask;

        /* next time we want to cond_resched() */
        struct xchk_relax               relax;

        /* State tracking for single-AG operations. */
        struct xchk_ag                  sa;

        /* State tracking for realtime operations. */
        struct xchk_rt                  sr;
};

/* XCHK state flags grow up from zero, XREP state flags grown down from 2^31 */
#define XCHK_TRY_HARDER         (1U << 0)  /* can't get resources, try again */
#define XCHK_HAVE_FREEZE_PROT   (1U << 1)  /* do we have freeze protection? */
#define XCHK_FSGATES_DRAIN      (1U << 2)  /* defer ops draining enabled */
#define XCHK_NEED_DRAIN         (1U << 3)  /* scrub needs to drain defer ops */
#define XCHK_FSGATES_QUOTA      (1U << 4)  /* quota live update enabled */
#define XCHK_FSGATES_DIRENTS    (1U << 5)  /* directory live update enabled */
#define XCHK_FSGATES_RMAP       (1U << 6)  /* rmapbt live update enabled */
#define XREP_RESET_PERAG_RESV   (1U << 30) /* must reset AG space reservation */
#define XREP_ALREADY_FIXED      (1U << 31) /* checking our repair work */

/*
 * The XCHK_FSGATES* flags reflect functionality in the main filesystem that
 * are only enabled for this particular online fsck.  When not in use, the
 * features are gated off via dynamic code patching, which is why the state
 * must be enabled during scrub setup and can only be torn down afterwards.
 */
#define XCHK_FSGATES_ALL        (XCHK_FSGATES_DRAIN | \
                                 XCHK_FSGATES_QUOTA | \
                                 XCHK_FSGATES_DIRENTS | \
                                 XCHK_FSGATES_RMAP)

struct xfs_scrub_subord {
        struct xfs_scrub        sc;
        struct xfs_scrub        *parent_sc;
        unsigned int            old_smtype;
        unsigned int            old_smflags;
};

struct xfs_scrub_subord *xchk_scrub_create_subord(struct xfs_scrub *sc,
                unsigned int subtype);
void xchk_scrub_free_subord(struct xfs_scrub_subord *sub);

/*
 * We /could/ terminate a scrub/repair operation early.  If we're not
 * in a good place to continue (fatal signal, etc.) then bail out.
 * Note that we're careful not to make any judgements about *error.
 */
static inline bool
xchk_should_terminate(
        struct xfs_scrub        *sc,
        int                     *error)
{
        if (xchk_maybe_relax(&sc->relax)) {
                if (*error == 0)
                        *error = -EINTR;
                return true;
        }
        return false;
}

static inline int xchk_nothing(struct xfs_scrub *sc)
{
        return -ENOENT;
}

/* Metadata scrubbers */
int xchk_tester(struct xfs_scrub *sc);
int xchk_superblock(struct xfs_scrub *sc);
int xchk_agf(struct xfs_scrub *sc);
int xchk_agfl(struct xfs_scrub *sc);
int xchk_agi(struct xfs_scrub *sc);
int xchk_allocbt(struct xfs_scrub *sc);
int xchk_iallocbt(struct xfs_scrub *sc);
int xchk_rmapbt(struct xfs_scrub *sc);
int xchk_refcountbt(struct xfs_scrub *sc);
int xchk_inode(struct xfs_scrub *sc);
int xchk_bmap_data(struct xfs_scrub *sc);
int xchk_bmap_attr(struct xfs_scrub *sc);
int xchk_bmap_cow(struct xfs_scrub *sc);
int xchk_directory(struct xfs_scrub *sc);
int xchk_xattr(struct xfs_scrub *sc);
int xchk_symlink(struct xfs_scrub *sc);
int xchk_parent(struct xfs_scrub *sc);
int xchk_dirtree(struct xfs_scrub *sc);
int xchk_metapath(struct xfs_scrub *sc);
#ifdef CONFIG_XFS_RT
int xchk_rtbitmap(struct xfs_scrub *sc);
int xchk_rtsummary(struct xfs_scrub *sc);
int xchk_rgsuperblock(struct xfs_scrub *sc);
int xchk_rtrmapbt(struct xfs_scrub *sc);
int xchk_rtrefcountbt(struct xfs_scrub *sc);
#else
# define xchk_rtbitmap          xchk_nothing
# define xchk_rtsummary         xchk_nothing
# define xchk_rgsuperblock      xchk_nothing
# define xchk_rtrmapbt          xchk_nothing
# define xchk_rtrefcountbt      xchk_nothing
#endif
#ifdef CONFIG_XFS_QUOTA
int xchk_quota(struct xfs_scrub *sc);
int xchk_quotacheck(struct xfs_scrub *sc);
#else
# define xchk_quota             xchk_nothing
# define xchk_quotacheck        xchk_nothing
#endif
int xchk_fscounters(struct xfs_scrub *sc);
int xchk_nlinks(struct xfs_scrub *sc);

/* cross-referencing helpers */
void xchk_xref_is_used_space(struct xfs_scrub *sc, xfs_agblock_t agbno,
                xfs_extlen_t len);
void xchk_xref_is_not_inode_chunk(struct xfs_scrub *sc, xfs_agblock_t agbno,
                xfs_extlen_t len);
void xchk_xref_is_inode_chunk(struct xfs_scrub *sc, xfs_agblock_t agbno,
                xfs_extlen_t len);
void xchk_xref_is_only_owned_by(struct xfs_scrub *sc, xfs_agblock_t agbno,
                xfs_extlen_t len, const struct xfs_owner_info *oinfo);
void xchk_xref_is_not_owned_by(struct xfs_scrub *sc, xfs_agblock_t agbno,
                xfs_extlen_t len, const struct xfs_owner_info *oinfo);
void xchk_xref_has_no_owner(struct xfs_scrub *sc, xfs_agblock_t agbno,
                xfs_extlen_t len);
void xchk_xref_is_cow_staging(struct xfs_scrub *sc, xfs_agblock_t bno,
                xfs_extlen_t len);
void xchk_xref_is_not_shared(struct xfs_scrub *sc, xfs_agblock_t bno,
                xfs_extlen_t len);
void xchk_xref_is_not_cow_staging(struct xfs_scrub *sc, xfs_agblock_t bno,
                xfs_extlen_t len);
#ifdef CONFIG_XFS_RT
void xchk_xref_is_used_rt_space(struct xfs_scrub *sc, xfs_rtblock_t rtbno,
                xfs_extlen_t len);
void xchk_xref_has_no_rt_owner(struct xfs_scrub *sc, xfs_rgblock_t rgbno,
                xfs_extlen_t len);
void xchk_xref_has_rt_owner(struct xfs_scrub *sc, xfs_rgblock_t rgbno,
                xfs_extlen_t len);
void xchk_xref_is_only_rt_owned_by(struct xfs_scrub *sc, xfs_rgblock_t rgbno,
                xfs_extlen_t len, const struct xfs_owner_info *oinfo);
void xchk_xref_is_rt_cow_staging(struct xfs_scrub *sc, xfs_rgblock_t rgbno,
                xfs_extlen_t len);
void xchk_xref_is_not_rt_shared(struct xfs_scrub *sc, xfs_rgblock_t rgbno,
                xfs_extlen_t len);
void xchk_xref_is_not_rt_cow_staging(struct xfs_scrub *sc, xfs_rgblock_t rgbno,
                xfs_extlen_t len);
#else
# define xchk_xref_is_used_rt_space(sc, rtbno, len) do { } while (0)
# define xchk_xref_has_no_rt_owner(sc, rtbno, len) do { } while (0)
# define xchk_xref_has_rt_owner(sc, rtbno, len) do { } while (0)
# define xchk_xref_is_only_rt_owned_by(sc, bno, len, oinfo) do { } while (0)
# define xchk_xref_is_rt_cow_staging(sc, bno, len) do { } while (0)
# define xchk_xref_is_not_rt_shared(sc, bno, len) do { } while (0)
# define xchk_xref_is_not_rt_cow_staging(sc, bno, len) do { } while (0)
#endif

#endif  /* __XFS_SCRUB_SCRUB_H__ */