mm: fix exec activate_mm vs TLB shootdown and lazy tlb switching race

[linux/fpc-iii.git] / fs / xfs / xfs_attr_list.c

/*
 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * Copyright (c) 2013 Red Hat, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_bit.h"
#include "xfs_mount.h"
#include "xfs_da_format.h"
#include "xfs_da_btree.h"
#include "xfs_inode.h"
#include "xfs_trans.h"
#include "xfs_inode_item.h"
#include "xfs_bmap.h"
#include "xfs_attr.h"
#include "xfs_attr_sf.h"
#include "xfs_attr_remote.h"
#include "xfs_attr_leaf.h"
#include "xfs_error.h"
#include "xfs_trace.h"
#include "xfs_buf_item.h"
#include "xfs_cksum.h"
#include "xfs_dir2.h"

STATIC int
xfs_attr_shortform_compare(const void *a, const void *b)
{
        xfs_attr_sf_sort_t *sa, *sb;

        sa = (xfs_attr_sf_sort_t *)a;
        sb = (xfs_attr_sf_sort_t *)b;
        if (sa->hash < sb->hash) {
                return -1;
        } else if (sa->hash > sb->hash) {
                return 1;
        } else {
                return sa->entno - sb->entno;
        }
}

#define XFS_ISRESET_CURSOR(cursor) \
        (!((cursor)->initted) && !((cursor)->hashval) && \
         !((cursor)->blkno) && !((cursor)->offset))
/*
 * Copy out entries of shortform attribute lists for attr_list().
 * Shortform attribute lists are not stored in hashval sorted order.
 * If the output buffer is not large enough to hold them all, then we
 * we have to calculate each entries' hashvalue and sort them before
 * we can begin returning them to the user.
 */
static int
xfs_attr_shortform_list(xfs_attr_list_context_t *context)
{
        attrlist_cursor_kern_t *cursor;
        xfs_attr_sf_sort_t *sbuf, *sbp;
        xfs_attr_shortform_t *sf;
        xfs_attr_sf_entry_t *sfe;
        xfs_inode_t *dp;
        int sbsize, nsbuf, count, i;

        ASSERT(context != NULL);
        dp = context->dp;
        ASSERT(dp != NULL);
        ASSERT(dp->i_afp != NULL);
        sf = (xfs_attr_shortform_t *)dp->i_afp->if_u1.if_data;
        ASSERT(sf != NULL);
        if (!sf->hdr.count)
                return 0;
        cursor = context->cursor;
        ASSERT(cursor != NULL);

        trace_xfs_attr_list_sf(context);

        /*
         * If the buffer is large enough and the cursor is at the start,
         * do not bother with sorting since we will return everything in
         * one buffer and another call using the cursor won't need to be
         * made.
         * Note the generous fudge factor of 16 overhead bytes per entry.
         * If bufsize is zero then put_listent must be a search function
         * and can just scan through what we have.
         */
        if (context->bufsize == 0 ||
            (XFS_ISRESET_CURSOR(cursor) &&
             (dp->i_afp->if_bytes + sf->hdr.count * 16) < context->bufsize)) {
                for (i = 0, sfe = &sf->list[0]; i < sf->hdr.count; i++) {
                        context->put_listent(context,
                                             sfe->flags,
                                             sfe->nameval,
                                             (int)sfe->namelen,
                                             (int)sfe->valuelen);
                        /*
                         * Either search callback finished early or
                         * didn't fit it all in the buffer after all.
                         */
                        if (context->seen_enough)
                                break;
                        sfe = XFS_ATTR_SF_NEXTENTRY(sfe);
                }
                trace_xfs_attr_list_sf_all(context);
                return 0;
        }

        /* do no more for a search callback */
        if (context->bufsize == 0)
                return 0;

        /*
         * It didn't all fit, so we have to sort everything on hashval.
         */
        sbsize = sf->hdr.count * sizeof(*sbuf);
        sbp = sbuf = kmem_alloc(sbsize, KM_SLEEP | KM_NOFS);

        /*
         * Scan the attribute list for the rest of the entries, storing
         * the relevant info from only those that match into a buffer.
         */
        nsbuf = 0;
        for (i = 0, sfe = &sf->list[0]; i < sf->hdr.count; i++) {
                if (unlikely(
                    ((char *)sfe < (char *)sf) ||
                    ((char *)sfe >= ((char *)sf + dp->i_afp->if_bytes)))) {
                        XFS_CORRUPTION_ERROR("xfs_attr_shortform_list",
                                             XFS_ERRLEVEL_LOW,
                                             context->dp->i_mount, sfe);
                        kmem_free(sbuf);
                        return -EFSCORRUPTED;
                }

                sbp->entno = i;
                sbp->hash = xfs_da_hashname(sfe->nameval, sfe->namelen);
                sbp->name = sfe->nameval;
                sbp->namelen = sfe->namelen;
                /* These are bytes, and both on-disk, don't endian-flip */
                sbp->valuelen = sfe->valuelen;
                sbp->flags = sfe->flags;
                sfe = XFS_ATTR_SF_NEXTENTRY(sfe);
                sbp++;
                nsbuf++;
        }

        /*
         * Sort the entries on hash then entno.
         */
        xfs_sort(sbuf, nsbuf, sizeof(*sbuf), xfs_attr_shortform_compare);

        /*
         * Re-find our place IN THE SORTED LIST.
         */
        count = 0;
        cursor->initted = 1;
        cursor->blkno = 0;
        for (sbp = sbuf, i = 0; i < nsbuf; i++, sbp++) {
                if (sbp->hash == cursor->hashval) {
                        if (cursor->offset == count) {
                                break;
                        }
                        count++;
                } else if (sbp->hash > cursor->hashval) {
                        break;
                }
        }
        if (i == nsbuf) {
                kmem_free(sbuf);
                return 0;
        }

        /*
         * Loop putting entries into the user buffer.
         */
        for ( ; i < nsbuf; i++, sbp++) {
                if (cursor->hashval != sbp->hash) {
                        cursor->hashval = sbp->hash;
                        cursor->offset = 0;
                }
                context->put_listent(context,
                                     sbp->flags,
                                     sbp->name,
                                     sbp->namelen,
                                     sbp->valuelen);
                if (context->seen_enough)
                        break;
                cursor->offset++;
        }

        kmem_free(sbuf);
        return 0;
}

STATIC int
xfs_attr_node_list(xfs_attr_list_context_t *context)
{
        attrlist_cursor_kern_t *cursor;
        xfs_attr_leafblock_t *leaf;
        xfs_da_intnode_t *node;
        struct xfs_attr3_icleaf_hdr leafhdr;
        struct xfs_da3_icnode_hdr nodehdr;
        struct xfs_da_node_entry *btree;
        int error, i;
        struct xfs_buf *bp;
        struct xfs_inode        *dp = context->dp;
        struct xfs_mount        *mp = dp->i_mount;

        trace_xfs_attr_node_list(context);

        cursor = context->cursor;
        cursor->initted = 1;

        /*
         * Do all sorts of validation on the passed-in cursor structure.
         * If anything is amiss, ignore the cursor and look up the hashval
         * starting from the btree root.
         */
        bp = NULL;
        if (cursor->blkno > 0) {
                error = xfs_da3_node_read(context->tp, dp, cursor->blkno, -1,
                                              &bp, XFS_ATTR_FORK);
                if ((error != 0) && (error != -EFSCORRUPTED))
                        return error;
                if (bp) {
                        struct xfs_attr_leaf_entry *entries;

                        node = bp->b_addr;
                        switch (be16_to_cpu(node->hdr.info.magic)) {
                        case XFS_DA_NODE_MAGIC:
                        case XFS_DA3_NODE_MAGIC:
                                trace_xfs_attr_list_wrong_blk(context);
                                xfs_trans_brelse(context->tp, bp);
                                bp = NULL;
                                break;
                        case XFS_ATTR_LEAF_MAGIC:
                        case XFS_ATTR3_LEAF_MAGIC:
                                leaf = bp->b_addr;
                                xfs_attr3_leaf_hdr_from_disk(mp->m_attr_geo,
                                                             &leafhdr, leaf);
                                entries = xfs_attr3_leaf_entryp(leaf);
                                if (cursor->hashval > be32_to_cpu(
                                                entries[leafhdr.count - 1].hashval)) {
                                        trace_xfs_attr_list_wrong_blk(context);
                                        xfs_trans_brelse(context->tp, bp);
                                        bp = NULL;
                                } else if (cursor->hashval <= be32_to_cpu(
                                                entries[0].hashval)) {
                                        trace_xfs_attr_list_wrong_blk(context);
                                        xfs_trans_brelse(context->tp, bp);
                                        bp = NULL;
                                }
                                break;
                        default:
                                trace_xfs_attr_list_wrong_blk(context);
                                xfs_trans_brelse(context->tp, bp);
                                bp = NULL;
                        }
                }
        }

        /*
         * We did not find what we expected given the cursor's contents,
         * so we start from the top and work down based on the hash value.
         * Note that start of node block is same as start of leaf block.
         */
        if (bp == NULL) {
                cursor->blkno = 0;
                for (;;) {
                        uint16_t magic;

                        error = xfs_da3_node_read(context->tp, dp,
                                                      cursor->blkno, -1, &bp,
                                                      XFS_ATTR_FORK);
                        if (error)
                                return error;
                        node = bp->b_addr;
                        magic = be16_to_cpu(node->hdr.info.magic);
                        if (magic == XFS_ATTR_LEAF_MAGIC ||
                            magic == XFS_ATTR3_LEAF_MAGIC)
                                break;
                        if (magic != XFS_DA_NODE_MAGIC &&
                            magic != XFS_DA3_NODE_MAGIC) {
                                XFS_CORRUPTION_ERROR("xfs_attr_node_list(3)",
                                                     XFS_ERRLEVEL_LOW,
                                                     context->dp->i_mount,
                                                     node);
                                xfs_trans_brelse(context->tp, bp);
                                return -EFSCORRUPTED;
                        }

                        dp->d_ops->node_hdr_from_disk(&nodehdr, node);
                        btree = dp->d_ops->node_tree_p(node);
                        for (i = 0; i < nodehdr.count; btree++, i++) {
                                if (cursor->hashval
                                                <= be32_to_cpu(btree->hashval)) {
                                        cursor->blkno = be32_to_cpu(btree->before);
                                        trace_xfs_attr_list_node_descend(context,
                                                                         btree);
                                        break;
                                }
                        }
                        if (i == nodehdr.count) {
                                xfs_trans_brelse(context->tp, bp);
                                return 0;
                        }
                        xfs_trans_brelse(context->tp, bp);
                }
        }
        ASSERT(bp != NULL);

        /*
         * Roll upward through the blocks, processing each leaf block in
         * order.  As long as there is space in the result buffer, keep
         * adding the information.
         */
        for (;;) {
                leaf = bp->b_addr;
                xfs_attr3_leaf_list_int(bp, context);
                xfs_attr3_leaf_hdr_from_disk(mp->m_attr_geo, &leafhdr, leaf);
                if (context->seen_enough || leafhdr.forw == 0)
                        break;
                cursor->blkno = leafhdr.forw;
                xfs_trans_brelse(context->tp, bp);
                error = xfs_attr3_leaf_read(context->tp, dp, cursor->blkno, -1, &bp);
                if (error)
                        return error;
        }
        xfs_trans_brelse(context->tp, bp);
        return 0;
}

/*
 * Copy out attribute list entries for attr_list(), for leaf attribute lists.
 */
void
xfs_attr3_leaf_list_int(
        struct xfs_buf                  *bp,
        struct xfs_attr_list_context    *context)
{
        struct attrlist_cursor_kern     *cursor;
        struct xfs_attr_leafblock       *leaf;
        struct xfs_attr3_icleaf_hdr     ichdr;
        struct xfs_attr_leaf_entry      *entries;
        struct xfs_attr_leaf_entry      *entry;
        int                             i;
        struct xfs_mount                *mp = context->dp->i_mount;

        trace_xfs_attr_list_leaf(context);

        leaf = bp->b_addr;
        xfs_attr3_leaf_hdr_from_disk(mp->m_attr_geo, &ichdr, leaf);
        entries = xfs_attr3_leaf_entryp(leaf);

        cursor = context->cursor;
        cursor->initted = 1;

        /*
         * Re-find our place in the leaf block if this is a new syscall.
         */
        if (context->resynch) {
                entry = &entries[0];
                for (i = 0; i < ichdr.count; entry++, i++) {
                        if (be32_to_cpu(entry->hashval) == cursor->hashval) {
                                if (cursor->offset == context->dupcnt) {
                                        context->dupcnt = 0;
                                        break;
                                }
                                context->dupcnt++;
                        } else if (be32_to_cpu(entry->hashval) >
                                        cursor->hashval) {
                                context->dupcnt = 0;
                                break;
                        }
                }
                if (i == ichdr.count) {
                        trace_xfs_attr_list_notfound(context);
                        return;
                }
        } else {
                entry = &entries[0];
                i = 0;
        }
        context->resynch = 0;

        /*
         * We have found our place, start copying out the new attributes.
         */
        for (; i < ichdr.count; entry++, i++) {
                char *name;
                int namelen, valuelen;

                if (be32_to_cpu(entry->hashval) != cursor->hashval) {
                        cursor->hashval = be32_to_cpu(entry->hashval);
                        cursor->offset = 0;
                }

                if (entry->flags & XFS_ATTR_INCOMPLETE)
                        continue;               /* skip incomplete entries */

                if (entry->flags & XFS_ATTR_LOCAL) {
                        xfs_attr_leaf_name_local_t *name_loc;

                        name_loc = xfs_attr3_leaf_name_local(leaf, i);
                        name = name_loc->nameval;
                        namelen = name_loc->namelen;
                        valuelen = be16_to_cpu(name_loc->valuelen);
                } else {
                        xfs_attr_leaf_name_remote_t *name_rmt;

                        name_rmt = xfs_attr3_leaf_name_remote(leaf, i);
                        name = name_rmt->name;
                        namelen = name_rmt->namelen;
                        valuelen = be32_to_cpu(name_rmt->valuelen);
                }

                context->put_listent(context, entry->flags,
                                              name, namelen, valuelen);
                if (context->seen_enough)
                        break;
                cursor->offset++;
        }
        trace_xfs_attr_list_leaf_end(context);
        return;
}

/*
 * Copy out attribute entries for attr_list(), for leaf attribute lists.
 */
STATIC int
xfs_attr_leaf_list(xfs_attr_list_context_t *context)
{
        int error;
        struct xfs_buf *bp;

        trace_xfs_attr_leaf_list(context);

        context->cursor->blkno = 0;
        error = xfs_attr3_leaf_read(context->tp, context->dp, 0, -1, &bp);
        if (error)
                return error;

        xfs_attr3_leaf_list_int(bp, context);
        xfs_trans_brelse(context->tp, bp);
        return 0;
}

int
xfs_attr_list_int_ilocked(
        struct xfs_attr_list_context    *context)
{
        struct xfs_inode                *dp = context->dp;

        ASSERT(xfs_isilocked(dp, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));

        /*
         * Decide on what work routines to call based on the inode size.
         */
        if (!xfs_inode_hasattr(dp))
                return 0;
        else if (dp->i_d.di_aformat == XFS_DINODE_FMT_LOCAL)
                return xfs_attr_shortform_list(context);
        else if (xfs_bmap_one_block(dp, XFS_ATTR_FORK))
                return xfs_attr_leaf_list(context);
        return xfs_attr_node_list(context);
}

int
xfs_attr_list_int(
        xfs_attr_list_context_t *context)
{
        int error;
        xfs_inode_t *dp = context->dp;
        uint            lock_mode;

        XFS_STATS_INC(dp->i_mount, xs_attr_list);

        if (XFS_FORCED_SHUTDOWN(dp->i_mount))
                return -EIO;

        lock_mode = xfs_ilock_attr_map_shared(dp);
        error = xfs_attr_list_int_ilocked(context);
        xfs_iunlock(dp, lock_mode);
        return error;
}

#define ATTR_ENTBASESIZE                /* minimum bytes used by an attr */ \
        (((struct attrlist_ent *) 0)->a_name - (char *) 0)
#define ATTR_ENTSIZE(namelen)           /* actual bytes used by an attr */ \
        ((ATTR_ENTBASESIZE + (namelen) + 1 + sizeof(u_int32_t)-1) \
         & ~(sizeof(u_int32_t)-1))

/*
 * Format an attribute and copy it out to the user's buffer.
 * Take care to check values and protect against them changing later,
 * we may be reading them directly out of a user buffer.
 */
STATIC void
xfs_attr_put_listent(
        xfs_attr_list_context_t *context,
        int             flags,
        unsigned char   *name,
        int             namelen,
        int             valuelen)
{
        struct attrlist *alist = (struct attrlist *)context->alist;
        attrlist_ent_t *aep;
        int arraytop;

        ASSERT(!(context->flags & ATTR_KERNOVAL));
        ASSERT(context->count >= 0);
        ASSERT(context->count < (ATTR_MAX_VALUELEN/8));
        ASSERT(context->firstu >= sizeof(*alist));
        ASSERT(context->firstu <= context->bufsize);

        /*
         * Only list entries in the right namespace.
         */
        if (((context->flags & ATTR_SECURE) == 0) !=
            ((flags & XFS_ATTR_SECURE) == 0))
                return;
        if (((context->flags & ATTR_ROOT) == 0) !=
            ((flags & XFS_ATTR_ROOT) == 0))
                return;

        arraytop = sizeof(*alist) +
                        context->count * sizeof(alist->al_offset[0]);
        context->firstu -= ATTR_ENTSIZE(namelen);
        if (context->firstu < arraytop) {
                trace_xfs_attr_list_full(context);
                alist->al_more = 1;
                context->seen_enough = 1;
                return;
        }

        aep = (attrlist_ent_t *)&context->alist[context->firstu];
        aep->a_valuelen = valuelen;
        memcpy(aep->a_name, name, namelen);
        aep->a_name[namelen] = 0;
        alist->al_offset[context->count++] = context->firstu;
        alist->al_count = context->count;
        trace_xfs_attr_list_add(context);
        return;
}

/*
 * Generate a list of extended attribute names and optionally
 * also value lengths.  Positive return value follows the XFS
 * convention of being an error, zero or negative return code
 * is the length of the buffer returned (negated), indicating
 * success.
 */
int
xfs_attr_list(
        xfs_inode_t     *dp,
        char            *buffer,
        int             bufsize,
        int             flags,
        attrlist_cursor_kern_t *cursor)
{
        xfs_attr_list_context_t context;
        struct attrlist *alist;
        int error;

        /*
         * Validate the cursor.
         */
        if (cursor->pad1 || cursor->pad2)
                return -EINVAL;
        if ((cursor->initted == 0) &&
            (cursor->hashval || cursor->blkno || cursor->offset))
                return -EINVAL;

        /*
         * Check for a properly aligned buffer.
         */
        if (((long)buffer) & (sizeof(int)-1))
                return -EFAULT;
        if (flags & ATTR_KERNOVAL)
                bufsize = 0;

        /*
         * Initialize the output buffer.
         */
        memset(&context, 0, sizeof(context));
        context.dp = dp;
        context.cursor = cursor;
        context.resynch = 1;
        context.flags = flags;
        context.alist = buffer;
        context.bufsize = (bufsize & ~(sizeof(int)-1));  /* align */
        context.firstu = context.bufsize;
        context.put_listent = xfs_attr_put_listent;

        alist = (struct attrlist *)context.alist;
        alist->al_count = 0;
        alist->al_more = 0;
        alist->al_offset[0] = context.bufsize;

        error = xfs_attr_list_int(&context);
        ASSERT(error <= 0);
        return error;
}