// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2000-2001,2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 */
#include "xfs_platform.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_inode.h"
#include "xfs_trans.h"
#include "xfs_bmap.h"
#include "xfs_dir2.h"
#include "xfs_dir2_priv.h"
#include "xfs_errortag.h"
#include "xfs_error.h"
#include "xfs_trace.h"
#include "xfs_health.h"
#include "xfs_bmap_btree.h"
#include "xfs_trans_space.h"
#include "xfs_parent.h"
#include "xfs_ag.h"
#include "xfs_ialloc.h"

const struct xfs_name xfs_name_dotdot = {
        .name   = (const unsigned char *)"..",
        .len    = 2,
        .type   = XFS_DIR3_FT_DIR,
};

const struct xfs_name xfs_name_dot = {
        .name   = (const unsigned char *)".",
        .len    = 1,
        .type   = XFS_DIR3_FT_DIR,
};

/*
 * Convert inode mode to directory entry filetype
 */
unsigned char
xfs_mode_to_ftype(
        int             mode)
{
        switch (mode & S_IFMT) {
        case S_IFREG:
                return XFS_DIR3_FT_REG_FILE;
        case S_IFDIR:
                return XFS_DIR3_FT_DIR;
        case S_IFCHR:
                return XFS_DIR3_FT_CHRDEV;
        case S_IFBLK:
                return XFS_DIR3_FT_BLKDEV;
        case S_IFIFO:
                return XFS_DIR3_FT_FIFO;
        case S_IFSOCK:
                return XFS_DIR3_FT_SOCK;
        case S_IFLNK:
                return XFS_DIR3_FT_SYMLINK;
        default:
                return XFS_DIR3_FT_UNKNOWN;
        }
}

/*
 * ASCII case-insensitive (ie. A-Z) support for directories that was
 * used in IRIX.
 */
xfs_dahash_t
xfs_ascii_ci_hashname(
        const struct xfs_name   *name)
{
        xfs_dahash_t            hash;
        int                     i;

        for (i = 0, hash = 0; i < name->len; i++)
                hash = xfs_ascii_ci_xfrm(name->name[i]) ^ rol32(hash, 7);

        return hash;
}

enum xfs_dacmp
xfs_ascii_ci_compname(
        struct xfs_da_args      *args,
        const unsigned char     *name,
        int                     len)
{
        enum xfs_dacmp          result;
        int                     i;

        if (args->namelen != len)
                return XFS_CMP_DIFFERENT;

        result = XFS_CMP_EXACT;
        for (i = 0; i < len; i++) {
                if (args->name[i] == name[i])
                        continue;
                if (xfs_ascii_ci_xfrm(args->name[i]) !=
                    xfs_ascii_ci_xfrm(name[i]))
                        return XFS_CMP_DIFFERENT;
                result = XFS_CMP_CASE;
        }

        return result;
}

int
xfs_da_mount(
        struct xfs_mount        *mp)
{
        struct xfs_da_geometry  *dageo;


        ASSERT(mp->m_sb.sb_versionnum & XFS_SB_VERSION_DIRV2BIT);
        ASSERT(xfs_dir2_dirblock_bytes(&mp->m_sb) <= XFS_MAX_BLOCKSIZE);

        mp->m_dir_geo = kzalloc_obj(struct xfs_da_geometry,
                                    GFP_KERNEL | __GFP_RETRY_MAYFAIL);
        mp->m_attr_geo = kzalloc_obj(struct xfs_da_geometry,
                                     GFP_KERNEL | __GFP_RETRY_MAYFAIL);
        if (!mp->m_dir_geo || !mp->m_attr_geo) {
                kfree(mp->m_dir_geo);
                kfree(mp->m_attr_geo);
                return -ENOMEM;
        }

        /* set up directory geometry */
        dageo = mp->m_dir_geo;
        dageo->blklog = mp->m_sb.sb_blocklog + mp->m_sb.sb_dirblklog;
        dageo->fsblog = mp->m_sb.sb_blocklog;
        dageo->blksize = xfs_dir2_dirblock_bytes(&mp->m_sb);
        dageo->fsbcount = 1 << mp->m_sb.sb_dirblklog;
        if (xfs_has_crc(mp)) {
                dageo->node_hdr_size = sizeof(struct xfs_da3_node_hdr);
                dageo->leaf_hdr_size = sizeof(struct xfs_dir3_leaf_hdr);
                dageo->free_hdr_size = sizeof(struct xfs_dir3_free_hdr);
                dageo->data_entry_offset =
                                sizeof(struct xfs_dir3_data_hdr);
        } else {
                dageo->node_hdr_size = sizeof(struct xfs_da_node_hdr);
                dageo->leaf_hdr_size = sizeof(struct xfs_dir2_leaf_hdr);
                dageo->free_hdr_size = sizeof(struct xfs_dir2_free_hdr);
                dageo->data_entry_offset =
                                sizeof(struct xfs_dir2_data_hdr);
        }
        dageo->leaf_max_ents = (dageo->blksize - dageo->leaf_hdr_size) /
                        sizeof(struct xfs_dir2_leaf_entry);
        dageo->free_max_bests = (dageo->blksize - dageo->free_hdr_size) /
                        sizeof(xfs_dir2_data_off_t);

        dageo->data_first_offset = dageo->data_entry_offset +
                        xfs_dir2_data_entsize(mp, 1) +
                        xfs_dir2_data_entsize(mp, 2);

        /*
         * Now we've set up the block conversion variables, we can calculate the
         * segment block constants using the geometry structure.
         */
        dageo->datablk = xfs_dir2_byte_to_da(dageo, XFS_DIR2_DATA_OFFSET);
        dageo->leafblk = xfs_dir2_byte_to_da(dageo, XFS_DIR2_LEAF_OFFSET);
        dageo->freeblk = xfs_dir2_byte_to_da(dageo, XFS_DIR2_FREE_OFFSET);
        dageo->node_ents = (dageo->blksize - dageo->node_hdr_size) /
                                (uint)sizeof(xfs_da_node_entry_t);
        dageo->max_extents = (XFS_DIR2_MAX_SPACES * XFS_DIR2_SPACE_SIZE) >>
                                        mp->m_sb.sb_blocklog;
        dageo->magicpct = (dageo->blksize * 37) / 100;

        /* set up attribute geometry - single fsb only */
        dageo = mp->m_attr_geo;
        dageo->blklog = mp->m_sb.sb_blocklog;
        dageo->fsblog = mp->m_sb.sb_blocklog;
        dageo->blksize = 1 << dageo->blklog;
        dageo->fsbcount = 1;
        dageo->node_hdr_size = mp->m_dir_geo->node_hdr_size;
        dageo->node_ents = (dageo->blksize - dageo->node_hdr_size) /
                                (uint)sizeof(xfs_da_node_entry_t);

        if (xfs_has_large_extent_counts(mp))
                dageo->max_extents = XFS_MAX_EXTCNT_ATTR_FORK_LARGE;
        else
                dageo->max_extents = XFS_MAX_EXTCNT_ATTR_FORK_SMALL;

        dageo->magicpct = (dageo->blksize * 37) / 100;
        return 0;
}

void
xfs_da_unmount(
        struct xfs_mount        *mp)
{
        kfree(mp->m_dir_geo);
        kfree(mp->m_attr_geo);
}

/*
 * Return 1 if directory contains only "." and "..".
 */
static bool
xfs_dir_isempty(
        xfs_inode_t     *dp)
{
        xfs_dir2_sf_hdr_t       *sfp;

        ASSERT(S_ISDIR(VFS_I(dp)->i_mode));
        if (dp->i_disk_size == 0)       /* might happen during shutdown. */
                return true;
        if (dp->i_disk_size > xfs_inode_data_fork_size(dp))
                return false;
        sfp = dp->i_df.if_data;
        return !sfp->count;
}

/*
 * Validate a given inode number.
 */
int
xfs_dir_ino_validate(
        xfs_mount_t     *mp,
        xfs_ino_t       ino)
{
        bool            ino_ok = xfs_verify_dir_ino(mp, ino);

        if (XFS_IS_CORRUPT(mp, !ino_ok) ||
            XFS_TEST_ERROR(mp, XFS_ERRTAG_DIR_INO_VALIDATE)) {
                xfs_warn(mp, "Invalid inode number 0x%Lx",
                                (unsigned long long) ino);
                return -EFSCORRUPTED;
        }
        return 0;
}

/*
 * Initialize a directory with its "." and ".." entries.
 */
int
xfs_dir_init(
        xfs_trans_t     *tp,
        xfs_inode_t     *dp,
        xfs_inode_t     *pdp)
{
        struct xfs_da_args *args;
        int             error;

        ASSERT(S_ISDIR(VFS_I(dp)->i_mode));
        error = xfs_dir_ino_validate(tp->t_mountp, pdp->i_ino);
        if (error)
                return error;

        args = kzalloc_obj(*args, GFP_KERNEL | __GFP_NOFAIL);
        if (!args)
                return -ENOMEM;

        args->geo = dp->i_mount->m_dir_geo;
        args->dp = dp;
        args->trans = tp;
        args->owner = dp->i_ino;
        error = xfs_dir2_sf_create(args, pdp->i_ino);
        kfree(args);
        return error;
}

enum xfs_dir2_fmt
xfs_dir2_format(
        struct xfs_da_args      *args,
        int                     *error)
{
        struct xfs_inode        *dp = args->dp;
        struct xfs_mount        *mp = dp->i_mount;
        struct xfs_da_geometry  *geo = mp->m_dir_geo;
        xfs_fileoff_t           eof;

        xfs_assert_ilocked(dp, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL);

        *error = 0;
        if (dp->i_df.if_format == XFS_DINODE_FMT_LOCAL)
                return XFS_DIR2_FMT_SF;

        *error = xfs_bmap_last_offset(dp, &eof, XFS_DATA_FORK);
        if (*error)
                return XFS_DIR2_FMT_ERROR;

        if (eof == XFS_B_TO_FSB(mp, geo->blksize)) {
                if (XFS_IS_CORRUPT(mp, dp->i_disk_size != geo->blksize)) {
                        xfs_da_mark_sick(args);
                        *error = -EFSCORRUPTED;
                        return XFS_DIR2_FMT_ERROR;
                }
                return XFS_DIR2_FMT_BLOCK;
        }
        if (eof == geo->leafblk + geo->fsbcount)
                return XFS_DIR2_FMT_LEAF;
        return XFS_DIR2_FMT_NODE;
}

int
xfs_dir_createname_args(
        struct xfs_da_args      *args)
{
        int                     error;

        if (!args->inumber)
                args->op_flags |= XFS_DA_OP_JUSTCHECK;

        switch (xfs_dir2_format(args, &error)) {
        case XFS_DIR2_FMT_SF:
                return xfs_dir2_sf_addname(args);
        case XFS_DIR2_FMT_BLOCK:
                return xfs_dir2_block_addname(args);
        case XFS_DIR2_FMT_LEAF:
                return xfs_dir2_leaf_addname(args);
        case XFS_DIR2_FMT_NODE:
                return xfs_dir2_node_addname(args);
        default:
                return error;
        }
}

/*
 * Enter a name in a directory, or check for available space.
 * If inum is 0, only the available space test is performed.
 */
int
xfs_dir_createname(
        struct xfs_trans        *tp,
        struct xfs_inode        *dp,
        const struct xfs_name   *name,
        xfs_ino_t               inum,           /* new entry inode number */
        xfs_extlen_t            total)          /* bmap's total block count */
{
        struct xfs_da_args      *args;
        int                     rval;

        ASSERT(S_ISDIR(VFS_I(dp)->i_mode));

        if (inum) {
                rval = xfs_dir_ino_validate(tp->t_mountp, inum);
                if (rval)
                        return rval;
                XFS_STATS_INC(dp->i_mount, xs_dir_create);
        }

        args = kzalloc_obj(*args, GFP_KERNEL | __GFP_NOFAIL);
        if (!args)
                return -ENOMEM;

        args->geo = dp->i_mount->m_dir_geo;
        args->name = name->name;
        args->namelen = name->len;
        args->filetype = name->type;
        args->hashval = xfs_dir2_hashname(dp->i_mount, name);
        args->inumber = inum;
        args->dp = dp;
        args->total = total;
        args->whichfork = XFS_DATA_FORK;
        args->trans = tp;
        args->op_flags = XFS_DA_OP_ADDNAME | XFS_DA_OP_OKNOENT;
        args->owner = dp->i_ino;

        rval = xfs_dir_createname_args(args);
        kfree(args);
        return rval;
}

/*
 * If doing a CI lookup and case-insensitive match, dup actual name into
 * args.value. Return EEXIST for success (ie. name found) or an error.
 */
int
xfs_dir_cilookup_result(
        struct xfs_da_args *args,
        const unsigned char *name,
        int             len)
{
        if (args->cmpresult == XFS_CMP_DIFFERENT)
                return -ENOENT;
        if (args->cmpresult != XFS_CMP_CASE ||
                                        !(args->op_flags & XFS_DA_OP_CILOOKUP))
                return -EEXIST;

        args->value = kmemdup(name, len,
                        GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_RETRY_MAYFAIL);
        if (!args->value)
                return -ENOMEM;

        args->valuelen = len;
        return -EEXIST;
}

int
xfs_dir_lookup_args(
        struct xfs_da_args      *args)
{
        int                     error;

        switch (xfs_dir2_format(args, &error)) {
        case XFS_DIR2_FMT_SF:
                error = xfs_dir2_sf_lookup(args);
                break;
        case XFS_DIR2_FMT_BLOCK:
                error = xfs_dir2_block_lookup(args);
                break;
        case XFS_DIR2_FMT_LEAF:
                error = xfs_dir2_leaf_lookup(args);
                break;
        case XFS_DIR2_FMT_NODE:
                error = xfs_dir2_node_lookup(args);
                break;
        default:
                break;
        }

        if (error != -EEXIST)
                return error;
        return 0;
}

/*
 * Lookup a name in a directory, give back the inode number.
 * If ci_name is not NULL, returns the actual name in ci_name if it differs
 * to name, or ci_name->name is set to NULL for an exact match.
 */

int
xfs_dir_lookup(
        struct xfs_trans        *tp,
        struct xfs_inode        *dp,
        const struct xfs_name   *name,
        xfs_ino_t               *inum,    /* out: inode number */
        struct xfs_name         *ci_name) /* out: actual name if CI match */
{
        struct xfs_da_args      *args;
        int                     rval;
        int                     lock_mode;

        ASSERT(S_ISDIR(VFS_I(dp)->i_mode));
        XFS_STATS_INC(dp->i_mount, xs_dir_lookup);

        args = kzalloc_obj(*args, GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);
        args->geo = dp->i_mount->m_dir_geo;
        args->name = name->name;
        args->namelen = name->len;
        args->filetype = name->type;
        args->hashval = xfs_dir2_hashname(dp->i_mount, name);
        args->dp = dp;
        args->whichfork = XFS_DATA_FORK;
        args->trans = tp;
        args->op_flags = XFS_DA_OP_OKNOENT;
        args->owner = dp->i_ino;
        if (ci_name)
                args->op_flags |= XFS_DA_OP_CILOOKUP;

        lock_mode = xfs_ilock_data_map_shared(dp);
        rval = xfs_dir_lookup_args(args);
        if (!rval) {
                *inum = args->inumber;
                if (ci_name) {
                        ci_name->name = args->value;
                        ci_name->len = args->valuelen;
                }
        }
        xfs_iunlock(dp, lock_mode);
        kfree(args);
        return rval;
}

int
xfs_dir_removename_args(
        struct xfs_da_args      *args)
{
        int                     error;

        switch (xfs_dir2_format(args, &error)) {
        case XFS_DIR2_FMT_SF:
                return xfs_dir2_sf_removename(args);
        case XFS_DIR2_FMT_BLOCK:
                return xfs_dir2_block_removename(args);
        case XFS_DIR2_FMT_LEAF:
                return xfs_dir2_leaf_removename(args);
        case XFS_DIR2_FMT_NODE:
                return xfs_dir2_node_removename(args);
        default:
                return error;
        }
}

/*
 * Remove an entry from a directory.
 */
int
xfs_dir_removename(
        struct xfs_trans        *tp,
        struct xfs_inode        *dp,
        const struct xfs_name   *name,
        xfs_ino_t               ino,
        xfs_extlen_t            total)          /* bmap's total block count */
{
        struct xfs_da_args      *args;
        int                     rval;

        ASSERT(S_ISDIR(VFS_I(dp)->i_mode));
        XFS_STATS_INC(dp->i_mount, xs_dir_remove);

        args = kzalloc_obj(*args, GFP_KERNEL | __GFP_NOFAIL);
        if (!args)
                return -ENOMEM;

        args->geo = dp->i_mount->m_dir_geo;
        args->name = name->name;
        args->namelen = name->len;
        args->filetype = name->type;
        args->hashval = xfs_dir2_hashname(dp->i_mount, name);
        args->inumber = ino;
        args->dp = dp;
        args->total = total;
        args->whichfork = XFS_DATA_FORK;
        args->trans = tp;
        args->owner = dp->i_ino;
        rval = xfs_dir_removename_args(args);
        kfree(args);
        return rval;
}

int
xfs_dir_replace_args(
        struct xfs_da_args      *args)
{
        int                     error;

        switch (xfs_dir2_format(args, &error)) {
        case XFS_DIR2_FMT_SF:
                return xfs_dir2_sf_replace(args);
        case XFS_DIR2_FMT_BLOCK:
                return xfs_dir2_block_replace(args);
        case XFS_DIR2_FMT_LEAF:
                return xfs_dir2_leaf_replace(args);
        case XFS_DIR2_FMT_NODE:
                return xfs_dir2_node_replace(args);
        default:
                return error;
        }
}

/*
 * Replace the inode number of a directory entry.
 */
int
xfs_dir_replace(
        struct xfs_trans        *tp,
        struct xfs_inode        *dp,
        const struct xfs_name   *name,          /* name of entry to replace */
        xfs_ino_t               inum,           /* new inode number */
        xfs_extlen_t            total)          /* bmap's total block count */
{
        struct xfs_da_args      *args;
        int                     rval;

        ASSERT(S_ISDIR(VFS_I(dp)->i_mode));

        rval = xfs_dir_ino_validate(tp->t_mountp, inum);
        if (rval)
                return rval;

        args = kzalloc_obj(*args, GFP_KERNEL | __GFP_NOFAIL);
        if (!args)
                return -ENOMEM;

        args->geo = dp->i_mount->m_dir_geo;
        args->name = name->name;
        args->namelen = name->len;
        args->filetype = name->type;
        args->hashval = xfs_dir2_hashname(dp->i_mount, name);
        args->inumber = inum;
        args->dp = dp;
        args->total = total;
        args->whichfork = XFS_DATA_FORK;
        args->trans = tp;
        args->owner = dp->i_ino;
        rval = xfs_dir_replace_args(args);
        kfree(args);
        return rval;
}

/*
 * See if this entry can be added to the directory without allocating space.
 */
int
xfs_dir_canenter(
        struct xfs_trans        *tp,
        struct xfs_inode        *dp,
        const struct xfs_name   *name)          /* name of entry to add */
{
        return xfs_dir_createname(tp, dp, name, 0, 0);
}

/*
 * Utility routines.
 */

/*
 * Add a block to the directory.
 *
 * This routine is for data and free blocks, not leaf/node blocks which are
 * handled by xfs_da_grow_inode.
 */
int
xfs_dir2_grow_inode(
        struct xfs_da_args      *args,
        int                     space,  /* v2 dir's space XFS_DIR2_xxx_SPACE */
        xfs_dir2_db_t           *dbp)   /* out: block number added */
{
        struct xfs_inode        *dp = args->dp;
        struct xfs_mount        *mp = dp->i_mount;
        xfs_fileoff_t           bno;    /* directory offset of new block */
        int                     count;  /* count of filesystem blocks */
        int                     error;

        trace_xfs_dir2_grow_inode(args, space);

        /*
         * Set lowest possible block in the space requested.
         */
        bno = XFS_B_TO_FSBT(mp, space * XFS_DIR2_SPACE_SIZE);
        count = args->geo->fsbcount;

        error = xfs_da_grow_inode_int(args, &bno, count);
        if (error)
                return error;

        *dbp = xfs_dir2_da_to_db(args->geo, (xfs_dablk_t)bno);

        /*
         * Update file's size if this is the data space and it grew.
         */
        if (space == XFS_DIR2_DATA_SPACE) {
                xfs_fsize_t     size;           /* directory file (data) size */

                size = XFS_FSB_TO_B(mp, bno + count);
                if (size > dp->i_disk_size) {
                        dp->i_disk_size = size;
                        xfs_trans_log_inode(args->trans, dp, XFS_ILOG_CORE);
                }
        }
        return 0;
}

/*
 * Remove the given block from the directory.
 * This routine is used for data and free blocks, leaf/node are done
 * by xfs_da_shrink_inode.
 */
int
xfs_dir2_shrink_inode(
        struct xfs_da_args      *args,
        xfs_dir2_db_t           db,
        struct xfs_buf          *bp)
{
        xfs_fileoff_t           bno;            /* directory file offset */
        xfs_dablk_t             da;             /* directory file offset */
        int                     done;           /* bunmap is finished */
        struct xfs_inode        *dp;
        int                     error;
        struct xfs_mount        *mp;
        struct xfs_trans        *tp;

        trace_xfs_dir2_shrink_inode(args, db);

        dp = args->dp;
        mp = dp->i_mount;
        tp = args->trans;
        da = xfs_dir2_db_to_da(args->geo, db);

        /* Unmap the fsblock(s). */
        error = xfs_bunmapi(tp, dp, da, args->geo->fsbcount, 0, 0, &done);
        if (error) {
                /*
                 * ENOSPC actually can happen if we're in a removename with no
                 * space reservation, and the resulting block removal would
                 * cause a bmap btree split or conversion from extents to btree.
                 * This can only happen for un-fragmented directory blocks,
                 * since you need to be punching out the middle of an extent.
                 * In this case we need to leave the block in the file, and not
                 * binval it.  So the block has to be in a consistent empty
                 * state and appropriately logged.  We don't free up the buffer,
                 * the caller can tell it hasn't happened since it got an error
                 * back.
                 */
                return error;
        }
        ASSERT(done);
        /*
         * Invalidate the buffer from the transaction.
         */
        xfs_trans_binval(tp, bp);
        /*
         * If it's not a data block, we're done.
         */
        if (db >= xfs_dir2_byte_to_db(args->geo, XFS_DIR2_LEAF_OFFSET))
                return 0;
        /*
         * If the block isn't the last one in the directory, we're done.
         */
        if (dp->i_disk_size > xfs_dir2_db_off_to_byte(args->geo, db + 1, 0))
                return 0;
        bno = da;
        if ((error = xfs_bmap_last_before(tp, dp, &bno, XFS_DATA_FORK))) {
                /*
                 * This can't really happen unless there's kernel corruption.
                 */
                return error;
        }
        if (db == args->geo->datablk)
                ASSERT(bno == 0);
        else
                ASSERT(bno > 0);
        /*
         * Set the size to the new last block.
         */
        dp->i_disk_size = XFS_FSB_TO_B(mp, bno);
        xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
        return 0;
}

/* Returns true if the directory entry name is valid. */
bool
xfs_dir2_namecheck(
        const void      *name,
        size_t          length)
{
        /*
         * MAXNAMELEN includes the trailing null, but (name/length) leave it
         * out, so use >= for the length check.
         */
        if (length >= MAXNAMELEN)
                return false;

        /* There shouldn't be any slashes or nulls here */
        return !memchr(name, '/', length) && !memchr(name, 0, length);
}

xfs_dahash_t
xfs_dir2_hashname(
        struct xfs_mount        *mp,
        const struct xfs_name   *name)
{
        if (unlikely(xfs_has_asciici(mp)))
                return xfs_ascii_ci_hashname(name);
        return xfs_da_hashname(name->name, name->len);
}

enum xfs_dacmp
xfs_dir2_compname(
        struct xfs_da_args      *args,
        const unsigned char     *name,
        int                     len)
{
        if (unlikely(xfs_has_asciici(args->dp->i_mount)))
                return xfs_ascii_ci_compname(args, name, len);
        return xfs_da_compname(args, name, len);
}

#ifdef CONFIG_XFS_LIVE_HOOKS
/*
 * Use a static key here to reduce the overhead of directory live update hooks.
 * If the compiler supports jump labels, the static branch will be replaced by
 * a nop sled when there are no hook users.  Online fsck is currently the only
 * caller, so this is a reasonable tradeoff.
 *
 * Note: Patching the kernel code requires taking the cpu hotplug lock.  Other
 * parts of the kernel allocate memory with that lock held, which means that
 * XFS callers cannot hold any locks that might be used by memory reclaim or
 * writeback when calling the static_branch_{inc,dec} functions.
 */
DEFINE_STATIC_XFS_HOOK_SWITCH(xfs_dir_hooks_switch);

void
xfs_dir_hook_disable(void)
{
        xfs_hooks_switch_off(&xfs_dir_hooks_switch);
}

void
xfs_dir_hook_enable(void)
{
        xfs_hooks_switch_on(&xfs_dir_hooks_switch);
}

/* Call hooks for a directory update relating to a child dirent update. */
inline void
xfs_dir_update_hook(
        struct xfs_inode                *dp,
        struct xfs_inode                *ip,
        int                             delta,
        const struct xfs_name           *name)
{
        if (xfs_hooks_switched_on(&xfs_dir_hooks_switch)) {
                struct xfs_dir_update_params    p = {
                        .dp             = dp,
                        .ip             = ip,
                        .delta          = delta,
                        .name           = name,
                };
                struct xfs_mount        *mp = ip->i_mount;

                xfs_hooks_call(&mp->m_dir_update_hooks, 0, &p);
        }
}

/* Call the specified function during a directory update. */
int
xfs_dir_hook_add(
        struct xfs_mount        *mp,
        struct xfs_dir_hook     *hook)
{
        return xfs_hooks_add(&mp->m_dir_update_hooks, &hook->dirent_hook);
}

/* Stop calling the specified function during a directory update. */
void
xfs_dir_hook_del(
        struct xfs_mount        *mp,
        struct xfs_dir_hook     *hook)
{
        xfs_hooks_del(&mp->m_dir_update_hooks, &hook->dirent_hook);
}

/* Configure directory update hook functions. */
void
xfs_dir_hook_setup(
        struct xfs_dir_hook     *hook,
        notifier_fn_t           mod_fn)
{
        xfs_hook_setup(&hook->dirent_hook, mod_fn);
}
#endif /* CONFIG_XFS_LIVE_HOOKS */

/*
 * Given a directory @dp, a newly allocated inode @ip, and a @name, link @ip
 * into @dp under the given @name.  If @ip is a directory, it will be
 * initialized.  Both inodes must have the ILOCK held and the transaction must
 * have sufficient blocks reserved.
 */
int
xfs_dir_create_child(
        struct xfs_trans        *tp,
        unsigned int            resblks,
        struct xfs_dir_update   *du)
{
        struct xfs_inode        *dp = du->dp;
        const struct xfs_name   *name = du->name;
        struct xfs_inode        *ip = du->ip;
        int                     error;

        xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
        xfs_assert_ilocked(dp, XFS_ILOCK_EXCL);

        error = xfs_dir_createname(tp, dp, name, ip->i_ino, resblks);
        if (error) {
                ASSERT(error != -ENOSPC);
                return error;
        }

        xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
        xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);

        if (S_ISDIR(VFS_I(ip)->i_mode)) {
                error = xfs_dir_init(tp, ip, dp);
                if (error)
                        return error;

                xfs_bumplink(tp, dp);
        }

        /*
         * If we have parent pointers, we need to add the attribute containing
         * the parent information now.
         */
        if (du->ppargs) {
                error = xfs_parent_addname(tp, du->ppargs, dp, name, ip);
                if (error)
                        return error;
        }

        xfs_dir_update_hook(dp, ip, 1, name);
        return 0;
}

/*
 * Given a directory @dp, an existing non-directory inode @ip, and a @name,
 * link @ip into @dp under the given @name.  Both inodes must have the ILOCK
 * held.
 */
int
xfs_dir_add_child(
        struct xfs_trans        *tp,
        unsigned int            resblks,
        struct xfs_dir_update   *du)
{
        struct xfs_inode        *dp = du->dp;
        const struct xfs_name   *name = du->name;
        struct xfs_inode        *ip = du->ip;
        struct xfs_mount        *mp = tp->t_mountp;
        int                     error;

        xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
        xfs_assert_ilocked(dp, XFS_ILOCK_EXCL);
        ASSERT(!S_ISDIR(VFS_I(ip)->i_mode));

        if (!resblks) {
                error = xfs_dir_canenter(tp, dp, name);
                if (error)
                        return error;
        }

        /*
         * Handle initial link state of O_TMPFILE inode
         */
        if (VFS_I(ip)->i_nlink == 0) {
                struct xfs_perag        *pag;

                pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
                error = xfs_iunlink_remove(tp, pag, ip);
                xfs_perag_put(pag);
                if (error)
                        return error;
        }

        error = xfs_dir_createname(tp, dp, name, ip->i_ino, resblks);
        if (error)
                return error;

        xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
        xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);

        xfs_bumplink(tp, ip);

        /*
         * If we have parent pointers, we now need to add the parent record to
         * the attribute fork of the inode. If this is the initial parent
         * attribute, we need to create it correctly, otherwise we can just add
         * the parent to the inode.
         */
        if (du->ppargs) {
                error = xfs_parent_addname(tp, du->ppargs, dp, name, ip);
                if (error)
                        return error;
        }

        xfs_dir_update_hook(dp, ip, 1, name);
        return 0;
}

/*
 * Given a directory @dp, a child @ip, and a @name, remove the (@name, @ip)
 * entry from the directory.  Both inodes must have the ILOCK held.
 */
int
xfs_dir_remove_child(
        struct xfs_trans        *tp,
        unsigned int            resblks,
        struct xfs_dir_update   *du)
{
        struct xfs_inode        *dp = du->dp;
        const struct xfs_name   *name = du->name;
        struct xfs_inode        *ip = du->ip;
        int                     error;

        xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
        xfs_assert_ilocked(dp, XFS_ILOCK_EXCL);

        /*
         * If we're removing a directory perform some additional validation.
         */
        if (S_ISDIR(VFS_I(ip)->i_mode)) {
                ASSERT(VFS_I(ip)->i_nlink >= 2);
                if (VFS_I(ip)->i_nlink != 2)
                        return -ENOTEMPTY;
                if (!xfs_dir_isempty(ip))
                        return -ENOTEMPTY;

                /* Drop the link from ip's "..".  */
                error = xfs_droplink(tp, dp);
                if (error)
                        return error;

                /* Drop the "." link from ip to self.  */
                error = xfs_droplink(tp, ip);
                if (error)
                        return error;

                /*
                 * Point the unlinked child directory's ".." entry to the root
                 * directory to eliminate back-references to inodes that may
                 * get freed before the child directory is closed.  If the fs
                 * gets shrunk, this can lead to dirent inode validation errors.
                 */
                if (dp->i_ino != tp->t_mountp->m_sb.sb_rootino) {
                        error = xfs_dir_replace(tp, ip, &xfs_name_dotdot,
                                        tp->t_mountp->m_sb.sb_rootino, 0);
                        if (error)
                                return error;
                }
        } else {
                /*
                 * When removing a non-directory we need to log the parent
                 * inode here.  For a directory this is done implicitly
                 * by the xfs_droplink call for the ".." entry.
                 */
                xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
        }
        xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);

        /* Drop the link from dp to ip. */
        error = xfs_droplink(tp, ip);
        if (error)
                return error;

        error = xfs_dir_removename(tp, dp, name, ip->i_ino, resblks);
        if (error) {
                ASSERT(error != -ENOENT);
                return error;
        }

        /* Remove parent pointer. */
        if (du->ppargs) {
                error = xfs_parent_removename(tp, du->ppargs, dp, name, ip);
                if (error)
                        return error;
        }

        xfs_dir_update_hook(dp, ip, -1, name);
        return 0;
}

/*
 * Exchange the entry (@name1, @ip1) in directory @dp1 with the entry (@name2,
 * @ip2) in directory @dp2, and update '..' @ip1 and @ip2's entries as needed.
 * @ip1 and @ip2 need not be of the same type.
 *
 * All inodes must have the ILOCK held, and both entries must already exist.
 */
int
xfs_dir_exchange_children(
        struct xfs_trans        *tp,
        struct xfs_dir_update   *du1,
        struct xfs_dir_update   *du2,
        unsigned int            spaceres)
{
        struct xfs_inode        *dp1 = du1->dp;
        const struct xfs_name   *name1 = du1->name;
        struct xfs_inode        *ip1 = du1->ip;
        struct xfs_inode        *dp2 = du2->dp;
        const struct xfs_name   *name2 = du2->name;
        struct xfs_inode        *ip2 = du2->ip;
        int                     ip1_flags = 0;
        int                     ip2_flags = 0;
        int                     dp2_flags = 0;
        int                     error;

        /* Swap inode number for dirent in first parent */
        error = xfs_dir_replace(tp, dp1, name1, ip2->i_ino, spaceres);
        if (error)
                return error;

        /* Swap inode number for dirent in second parent */
        error = xfs_dir_replace(tp, dp2, name2, ip1->i_ino, spaceres);
        if (error)
                return error;

        /*
         * If we're renaming one or more directories across different parents,
         * update the respective ".." entries (and link counts) to match the new
         * parents.
         */
        if (dp1 != dp2) {
                dp2_flags = XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG;

                if (S_ISDIR(VFS_I(ip2)->i_mode)) {
                        error = xfs_dir_replace(tp, ip2, &xfs_name_dotdot,
                                                dp1->i_ino, spaceres);
                        if (error)
                                return error;

                        /* transfer ip2 ".." reference to dp1 */
                        if (!S_ISDIR(VFS_I(ip1)->i_mode)) {
                                error = xfs_droplink(tp, dp2);
                                if (error)
                                        return error;
                                xfs_bumplink(tp, dp1);
                        }

                        /*
                         * Although ip1 isn't changed here, userspace needs
                         * to be warned about the change, so that applications
                         * relying on it (like backup ones), will properly
                         * notify the change
                         */
                        ip1_flags |= XFS_ICHGTIME_CHG;
                        ip2_flags |= XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG;
                }

                if (S_ISDIR(VFS_I(ip1)->i_mode)) {
                        error = xfs_dir_replace(tp, ip1, &xfs_name_dotdot,
                                                dp2->i_ino, spaceres);
                        if (error)
                                return error;

                        /* transfer ip1 ".." reference to dp2 */
                        if (!S_ISDIR(VFS_I(ip2)->i_mode)) {
                                error = xfs_droplink(tp, dp1);
                                if (error)
                                        return error;
                                xfs_bumplink(tp, dp2);
                        }

                        /*
                         * Although ip2 isn't changed here, userspace needs
                         * to be warned about the change, so that applications
                         * relying on it (like backup ones), will properly
                         * notify the change
                         */
                        ip1_flags |= XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG;
                        ip2_flags |= XFS_ICHGTIME_CHG;
                }
        }

        if (ip1_flags) {
                xfs_trans_ichgtime(tp, ip1, ip1_flags);
                xfs_trans_log_inode(tp, ip1, XFS_ILOG_CORE);
        }
        if (ip2_flags) {
                xfs_trans_ichgtime(tp, ip2, ip2_flags);
                xfs_trans_log_inode(tp, ip2, XFS_ILOG_CORE);
        }
        if (dp2_flags) {
                xfs_trans_ichgtime(tp, dp2, dp2_flags);
                xfs_trans_log_inode(tp, dp2, XFS_ILOG_CORE);
        }
        xfs_trans_ichgtime(tp, dp1, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
        xfs_trans_log_inode(tp, dp1, XFS_ILOG_CORE);

        /* Schedule parent pointer replacements */
        if (du1->ppargs) {
                error = xfs_parent_replacename(tp, du1->ppargs, dp1, name1,
                                dp2, name2, ip1);
                if (error)
                        return error;
        }

        if (du2->ppargs) {
                error = xfs_parent_replacename(tp, du2->ppargs, dp2, name2,
                                dp1, name1, ip2);
                if (error)
                        return error;
        }

        /*
         * Inform our hook clients that we've finished an exchange operation as
         * follows: removed the source and target files from their directories;
         * added the target to the source directory; and added the source to
         * the target directory.  All inodes are locked, so it's ok to model a
         * rename this way so long as we say we deleted entries before we add
         * new ones.
         */
        xfs_dir_update_hook(dp1, ip1, -1, name1);
        xfs_dir_update_hook(dp2, ip2, -1, name2);
        xfs_dir_update_hook(dp1, ip2, 1, name1);
        xfs_dir_update_hook(dp2, ip1, 1, name2);
        return 0;
}

/*
 * Given an entry (@src_name, @src_ip) in directory @src_dp, make the entry
 * @target_name in directory @target_dp point to @src_ip and remove the
 * original entry, cleaning up everything left behind.
 *
 * Cleanup involves dropping a link count on @target_ip, and either removing
 * the (@src_name, @src_ip) entry from @src_dp or simply replacing the entry
 * with (@src_name, @wip) if a whiteout inode @wip is supplied.
 *
 * All inodes must have the ILOCK held.  We assume that if @src_ip is a
 * directory then its '..' doesn't already point to @target_dp, and that @wip
 * is a freshly allocated whiteout.
 */
int
xfs_dir_rename_children(
        struct xfs_trans        *tp,
        struct xfs_dir_update   *du_src,
        struct xfs_dir_update   *du_tgt,
        unsigned int            spaceres,
        struct xfs_dir_update   *du_wip)
{
        struct xfs_mount        *mp = tp->t_mountp;
        struct xfs_inode        *src_dp = du_src->dp;
        const struct xfs_name   *src_name = du_src->name;
        struct xfs_inode        *src_ip = du_src->ip;
        struct xfs_inode        *target_dp = du_tgt->dp;
        const struct xfs_name   *target_name = du_tgt->name;
        struct xfs_inode        *target_ip = du_tgt->ip;
        bool                    new_parent = (src_dp != target_dp);
        bool                    src_is_directory;
        int                     error;

        src_is_directory = S_ISDIR(VFS_I(src_ip)->i_mode);

        /*
         * Check for expected errors before we dirty the transaction
         * so we can return an error without a transaction abort.
         */
        if (target_ip == NULL) {
                /*
                 * If there's no space reservation, check the entry will
                 * fit before actually inserting it.
                 */
                if (!spaceres) {
                        error = xfs_dir_canenter(tp, target_dp, target_name);
                        if (error)
                                return error;
                }
        } else {
                /*
                 * If target exists and it's a directory, check that whether
                 * it can be destroyed.
                 */
                if (S_ISDIR(VFS_I(target_ip)->i_mode) &&
                    (!xfs_dir_isempty(target_ip) ||
                     (VFS_I(target_ip)->i_nlink > 2)))
                        return -EEXIST;
        }

        /*
         * Directory entry creation below may acquire the AGF. Remove
         * the whiteout from the unlinked list first to preserve correct
         * AGI/AGF locking order. This dirties the transaction so failures
         * after this point will abort and log recovery will clean up the
         * mess.
         *
         * For whiteouts, we need to bump the link count on the whiteout
         * inode. After this point, we have a real link, clear the tmpfile
         * state flag from the inode so it doesn't accidentally get misused
         * in future.
         */
        if (du_wip->ip) {
                struct xfs_perag        *pag;

                ASSERT(VFS_I(du_wip->ip)->i_nlink == 0);

                pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, du_wip->ip->i_ino));
                error = xfs_iunlink_remove(tp, pag, du_wip->ip);
                xfs_perag_put(pag);
                if (error)
                        return error;

                xfs_bumplink(tp, du_wip->ip);
        }

        /*
         * Set up the target.
         */
        if (target_ip == NULL) {
                /*
                 * If target does not exist and the rename crosses
                 * directories, adjust the target directory link count
                 * to account for the ".." reference from the new entry.
                 */
                error = xfs_dir_createname(tp, target_dp, target_name,
                                           src_ip->i_ino, spaceres);
                if (error)
                        return error;

                xfs_trans_ichgtime(tp, target_dp,
                                        XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);

                if (new_parent && src_is_directory) {
                        xfs_bumplink(tp, target_dp);
                }
        } else { /* target_ip != NULL */
                /*
                 * Link the source inode under the target name.
                 * If the source inode is a directory and we are moving
                 * it across directories, its ".." entry will be
                 * inconsistent until we replace that down below.
                 *
                 * In case there is already an entry with the same
                 * name at the destination directory, remove it first.
                 */
                error = xfs_dir_replace(tp, target_dp, target_name,
                                        src_ip->i_ino, spaceres);
                if (error)
                        return error;

                xfs_trans_ichgtime(tp, target_dp,
                                        XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);

                /*
                 * Decrement the link count on the target since the target
                 * dir no longer points to it.
                 */
                error = xfs_droplink(tp, target_ip);
                if (error)
                        return error;

                if (src_is_directory) {
                        /*
                         * Drop the link from the old "." entry.
                         */
                        error = xfs_droplink(tp, target_ip);
                        if (error)
                                return error;
                }
        } /* target_ip != NULL */

        /*
         * Remove the source.
         */
        if (new_parent && src_is_directory) {
                /*
                 * Rewrite the ".." entry to point to the new
                 * directory.
                 */
                error = xfs_dir_replace(tp, src_ip, &xfs_name_dotdot,
                                        target_dp->i_ino, spaceres);
                ASSERT(error != -EEXIST);
                if (error)
                        return error;
        }

        /*
         * We always want to hit the ctime on the source inode.
         *
         * This isn't strictly required by the standards since the source
         * inode isn't really being changed, but old unix file systems did
         * it and some incremental backup programs won't work without it.
         */
        xfs_trans_ichgtime(tp, src_ip, XFS_ICHGTIME_CHG);
        xfs_trans_log_inode(tp, src_ip, XFS_ILOG_CORE);

        /*
         * Adjust the link count on src_dp.  This is necessary when
         * renaming a directory, either within one parent when
         * the target existed, or across two parent directories.
         */
        if (src_is_directory && (new_parent || target_ip != NULL)) {

                /*
                 * Decrement link count on src_directory since the
                 * entry that's moved no longer points to it.
                 */
                error = xfs_droplink(tp, src_dp);
                if (error)
                        return error;
        }

        /*
         * For whiteouts, we only need to update the source dirent with the
         * inode number of the whiteout inode rather than removing it
         * altogether.
         */
        if (du_wip->ip)
                error = xfs_dir_replace(tp, src_dp, src_name, du_wip->ip->i_ino,
                                        spaceres);
        else
                error = xfs_dir_removename(tp, src_dp, src_name, src_ip->i_ino,
                                           spaceres);
        if (error)
                return error;

        xfs_trans_ichgtime(tp, src_dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
        xfs_trans_log_inode(tp, src_dp, XFS_ILOG_CORE);
        if (new_parent)
                xfs_trans_log_inode(tp, target_dp, XFS_ILOG_CORE);

        /* Schedule parent pointer updates. */
        if (du_wip->ppargs) {
                error = xfs_parent_addname(tp, du_wip->ppargs, src_dp,
                                src_name, du_wip->ip);
                if (error)
                        return error;
        }

        if (du_src->ppargs) {
                error = xfs_parent_replacename(tp, du_src->ppargs, src_dp,
                                src_name, target_dp, target_name, src_ip);
                if (error)
                        return error;
        }

        if (du_tgt->ppargs) {
                error = xfs_parent_removename(tp, du_tgt->ppargs, target_dp,
                                target_name, target_ip);
                if (error)
                        return error;
        }

        /*
         * Inform our hook clients that we've finished a rename operation as
         * follows: removed the source and target files from their directories;
         * that we've added the source to the target directory; and finally
         * that we've added the whiteout, if there was one.  All inodes are
         * locked, so it's ok to model a rename this way so long as we say we
         * deleted entries before we add new ones.
         */
        if (target_ip)
                xfs_dir_update_hook(target_dp, target_ip, -1, target_name);
        xfs_dir_update_hook(src_dp, src_ip, -1, src_name);
        xfs_dir_update_hook(target_dp, src_ip, 1, target_name);
        if (du_wip->ip)
                xfs_dir_update_hook(src_dp, du_wip->ip, 1, src_name);
        return 0;
}