[mirror_ubuntu-artful-kernel.git] / fs / xfs / libxfs / xfs_attr_remote.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_shared.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_defer.h"
#include "xfs_da_format.h"
#include "xfs_da_btree.h"
#include "xfs_inode.h"
#include "xfs_alloc.h"
#include "xfs_trans.h"
#include "xfs_inode_item.h"
#include "xfs_bmap.h"
#include "xfs_bmap_util.h"
#include "xfs_attr.h"
#include "xfs_attr_leaf.h"
#include "xfs_attr_remote.h"
#include "xfs_trans_space.h"
#include "xfs_trace.h"
#include "xfs_cksum.h"
#include "xfs_buf_item.h"
#include "xfs_error.h"

#define ATTR_RMTVALUE_MAPSIZE   1       /* # of map entries at once */

/*
 * Each contiguous block has a header, so it is not just a simple attribute
 * length to FSB conversion.
 */
int
xfs_attr3_rmt_blocks(
        struct xfs_mount *mp,
        int             attrlen)
{
        if (xfs_sb_version_hascrc(&mp->m_sb)) {
                int buflen = XFS_ATTR3_RMT_BUF_SPACE(mp, mp->m_sb.sb_blocksize);
                return (attrlen + buflen - 1) / buflen;
        }
        return XFS_B_TO_FSB(mp, attrlen);
}

/*
 * Checking of the remote attribute header is split into two parts. The verifier
 * does CRC, location and bounds checking, the unpacking function checks the
 * attribute parameters and owner.
 */
static bool
xfs_attr3_rmt_hdr_ok(
        void                    *ptr,
        xfs_ino_t               ino,
        uint32_t                offset,
        uint32_t                size,
        xfs_daddr_t             bno)
{
        struct xfs_attr3_rmt_hdr *rmt = ptr;

        if (bno != be64_to_cpu(rmt->rm_blkno))
                return false;
        if (offset != be32_to_cpu(rmt->rm_offset))
                return false;
        if (size != be32_to_cpu(rmt->rm_bytes))
                return false;
        if (ino != be64_to_cpu(rmt->rm_owner))
                return false;

        /* ok */
        return true;
}

static bool
xfs_attr3_rmt_verify(
        struct xfs_mount        *mp,
        void                    *ptr,
        int                     fsbsize,
        xfs_daddr_t             bno)
{
        struct xfs_attr3_rmt_hdr *rmt = ptr;

        if (!xfs_sb_version_hascrc(&mp->m_sb))
                return false;
        if (rmt->rm_magic != cpu_to_be32(XFS_ATTR3_RMT_MAGIC))
                return false;
        if (!uuid_equal(&rmt->rm_uuid, &mp->m_sb.sb_meta_uuid))
                return false;
        if (be64_to_cpu(rmt->rm_blkno) != bno)
                return false;
        if (be32_to_cpu(rmt->rm_bytes) > fsbsize - sizeof(*rmt))
                return false;
        if (be32_to_cpu(rmt->rm_offset) +
                                be32_to_cpu(rmt->rm_bytes) > XFS_XATTR_SIZE_MAX)
                return false;
        if (rmt->rm_owner == 0)
                return false;

        return true;
}

static void
xfs_attr3_rmt_read_verify(
        struct xfs_buf  *bp)
{
        struct xfs_mount *mp = bp->b_target->bt_mount;
        char            *ptr;
        int             len;
        xfs_daddr_t     bno;
        int             blksize = mp->m_attr_geo->blksize;

        /* no verification of non-crc buffers */
        if (!xfs_sb_version_hascrc(&mp->m_sb))
                return;

        ptr = bp->b_addr;
        bno = bp->b_bn;
        len = BBTOB(bp->b_length);
        ASSERT(len >= blksize);

        while (len > 0) {
                if (!xfs_verify_cksum(ptr, blksize, XFS_ATTR3_RMT_CRC_OFF)) {
                        xfs_buf_ioerror(bp, -EFSBADCRC);
                        break;
                }
                if (!xfs_attr3_rmt_verify(mp, ptr, blksize, bno)) {
                        xfs_buf_ioerror(bp, -EFSCORRUPTED);
                        break;
                }
                len -= blksize;
                ptr += blksize;
                bno += BTOBB(blksize);
        }

        if (bp->b_error)
                xfs_verifier_error(bp);
        else
                ASSERT(len == 0);
}

static void
xfs_attr3_rmt_write_verify(
        struct xfs_buf  *bp)
{
        struct xfs_mount *mp = bp->b_target->bt_mount;
        int             blksize = mp->m_attr_geo->blksize;
        char            *ptr;
        int             len;
        xfs_daddr_t     bno;

        /* no verification of non-crc buffers */
        if (!xfs_sb_version_hascrc(&mp->m_sb))
                return;

        ptr = bp->b_addr;
        bno = bp->b_bn;
        len = BBTOB(bp->b_length);
        ASSERT(len >= blksize);

        while (len > 0) {
                struct xfs_attr3_rmt_hdr *rmt = (struct xfs_attr3_rmt_hdr *)ptr;

                if (!xfs_attr3_rmt_verify(mp, ptr, blksize, bno)) {
                        xfs_buf_ioerror(bp, -EFSCORRUPTED);
                        xfs_verifier_error(bp);
                        return;
                }

                /*
                 * Ensure we aren't writing bogus LSNs to disk. See
                 * xfs_attr3_rmt_hdr_set() for the explanation.
                 */
                if (rmt->rm_lsn != cpu_to_be64(NULLCOMMITLSN)) {
                        xfs_buf_ioerror(bp, -EFSCORRUPTED);
                        xfs_verifier_error(bp);
                        return;
                }
                xfs_update_cksum(ptr, blksize, XFS_ATTR3_RMT_CRC_OFF);

                len -= blksize;
                ptr += blksize;
                bno += BTOBB(blksize);
        }
        ASSERT(len == 0);
}

const struct xfs_buf_ops xfs_attr3_rmt_buf_ops = {
        .name = "xfs_attr3_rmt",
        .verify_read = xfs_attr3_rmt_read_verify,
        .verify_write = xfs_attr3_rmt_write_verify,
};

STATIC int
xfs_attr3_rmt_hdr_set(
        struct xfs_mount        *mp,
        void                    *ptr,
        xfs_ino_t               ino,
        uint32_t                offset,
        uint32_t                size,
        xfs_daddr_t             bno)
{
        struct xfs_attr3_rmt_hdr *rmt = ptr;

        if (!xfs_sb_version_hascrc(&mp->m_sb))
                return 0;

        rmt->rm_magic = cpu_to_be32(XFS_ATTR3_RMT_MAGIC);
        rmt->rm_offset = cpu_to_be32(offset);
        rmt->rm_bytes = cpu_to_be32(size);
        uuid_copy(&rmt->rm_uuid, &mp->m_sb.sb_meta_uuid);
        rmt->rm_owner = cpu_to_be64(ino);
        rmt->rm_blkno = cpu_to_be64(bno);

        /*
         * Remote attribute blocks are written synchronously, so we don't
         * have an LSN that we can stamp in them that makes any sense to log
         * recovery. To ensure that log recovery handles overwrites of these
         * blocks sanely (i.e. once they've been freed and reallocated as some
         * other type of metadata) we need to ensure that the LSN has a value
         * that tells log recovery to ignore the LSN and overwrite the buffer
         * with whatever is in it's log. To do this, we use the magic
         * NULLCOMMITLSN to indicate that the LSN is invalid.
         */
        rmt->rm_lsn = cpu_to_be64(NULLCOMMITLSN);

        return sizeof(struct xfs_attr3_rmt_hdr);
}

/*
 * Helper functions to copy attribute data in and out of the one disk extents
 */
STATIC int
xfs_attr_rmtval_copyout(
        struct xfs_mount *mp,
        struct xfs_buf  *bp,
        xfs_ino_t       ino,
        int             *offset,
        int             *valuelen,
        uint8_t         **dst)
{
        char            *src = bp->b_addr;
        xfs_daddr_t     bno = bp->b_bn;
        int             len = BBTOB(bp->b_length);
        int             blksize = mp->m_attr_geo->blksize;

        ASSERT(len >= blksize);

        while (len > 0 && *valuelen > 0) {
                int hdr_size = 0;
                int byte_cnt = XFS_ATTR3_RMT_BUF_SPACE(mp, blksize);

                byte_cnt = min(*valuelen, byte_cnt);

                if (xfs_sb_version_hascrc(&mp->m_sb)) {
                        if (!xfs_attr3_rmt_hdr_ok(src, ino, *offset,
                                                  byte_cnt, bno)) {
                                xfs_alert(mp,
"remote attribute header mismatch bno/off/len/owner (0x%llx/0x%x/Ox%x/0x%llx)",
                                        bno, *offset, byte_cnt, ino);
                                return -EFSCORRUPTED;
                        }
                        hdr_size = sizeof(struct xfs_attr3_rmt_hdr);
                }

                memcpy(*dst, src + hdr_size, byte_cnt);

                /* roll buffer forwards */
                len -= blksize;
                src += blksize;
                bno += BTOBB(blksize);

                /* roll attribute data forwards */
                *valuelen -= byte_cnt;
                *dst += byte_cnt;
                *offset += byte_cnt;
        }
        return 0;
}

STATIC void
xfs_attr_rmtval_copyin(
        struct xfs_mount *mp,
        struct xfs_buf  *bp,
        xfs_ino_t       ino,
        int             *offset,
        int             *valuelen,
        uint8_t         **src)
{
        char            *dst = bp->b_addr;
        xfs_daddr_t     bno = bp->b_bn;
        int             len = BBTOB(bp->b_length);
        int             blksize = mp->m_attr_geo->blksize;

        ASSERT(len >= blksize);

        while (len > 0 && *valuelen > 0) {
                int hdr_size;
                int byte_cnt = XFS_ATTR3_RMT_BUF_SPACE(mp, blksize);

                byte_cnt = min(*valuelen, byte_cnt);
                hdr_size = xfs_attr3_rmt_hdr_set(mp, dst, ino, *offset,
                                                 byte_cnt, bno);

                memcpy(dst + hdr_size, *src, byte_cnt);

                /*
                 * If this is the last block, zero the remainder of it.
                 * Check that we are actually the last block, too.
                 */
                if (byte_cnt + hdr_size < blksize) {
                        ASSERT(*valuelen - byte_cnt == 0);
                        ASSERT(len == blksize);
                        memset(dst + hdr_size + byte_cnt, 0,
                                        blksize - hdr_size - byte_cnt);
                }

                /* roll buffer forwards */
                len -= blksize;
                dst += blksize;
                bno += BTOBB(blksize);

                /* roll attribute data forwards */
                *valuelen -= byte_cnt;
                *src += byte_cnt;
                *offset += byte_cnt;
        }
}

/*
 * Read the value associated with an attribute from the out-of-line buffer
 * that we stored it in.
 */
int
xfs_attr_rmtval_get(
        struct xfs_da_args      *args)
{
        struct xfs_bmbt_irec    map[ATTR_RMTVALUE_MAPSIZE];
        struct xfs_mount        *mp = args->dp->i_mount;
        struct xfs_buf          *bp;
        xfs_dablk_t             lblkno = args->rmtblkno;
        uint8_t                 *dst = args->value;
        int                     valuelen;
        int                     nmap;
        int                     error;
        int                     blkcnt = args->rmtblkcnt;
        int                     i;
        int                     offset = 0;

        trace_xfs_attr_rmtval_get(args);

        ASSERT(!(args->flags & ATTR_KERNOVAL));
        ASSERT(args->rmtvaluelen == args->valuelen);

        valuelen = args->rmtvaluelen;
        while (valuelen > 0) {
                nmap = ATTR_RMTVALUE_MAPSIZE;
                error = xfs_bmapi_read(args->dp, (xfs_fileoff_t)lblkno,
                                       blkcnt, map, &nmap,
                                       XFS_BMAPI_ATTRFORK);
                if (error)
                        return error;
                ASSERT(nmap >= 1);

                for (i = 0; (i < nmap) && (valuelen > 0); i++) {
                        xfs_daddr_t     dblkno;
                        int             dblkcnt;

                        ASSERT((map[i].br_startblock != DELAYSTARTBLOCK) &&
                               (map[i].br_startblock != HOLESTARTBLOCK));
                        dblkno = XFS_FSB_TO_DADDR(mp, map[i].br_startblock);
                        dblkcnt = XFS_FSB_TO_BB(mp, map[i].br_blockcount);
                        error = xfs_trans_read_buf(mp, NULL, mp->m_ddev_targp,
                                                   dblkno, dblkcnt, 0, &bp,
                                                   &xfs_attr3_rmt_buf_ops);
                        if (error)
                                return error;

                        error = xfs_attr_rmtval_copyout(mp, bp, args->dp->i_ino,
                                                        &offset, &valuelen,
                                                        &dst);
                        xfs_buf_relse(bp);
                        if (error)
                                return error;

                        /* roll attribute extent map forwards */
                        lblkno += map[i].br_blockcount;
                        blkcnt -= map[i].br_blockcount;
                }
        }
        ASSERT(valuelen == 0);
        return 0;
}

/*
 * Write the value associated with an attribute into the out-of-line buffer
 * that we have defined for it.
 */
int
xfs_attr_rmtval_set(
        struct xfs_da_args      *args)
{
        struct xfs_inode        *dp = args->dp;
        struct xfs_mount        *mp = dp->i_mount;
        struct xfs_bmbt_irec    map;
        xfs_dablk_t             lblkno;
        xfs_fileoff_t           lfileoff = 0;
        uint8_t                 *src = args->value;
        int                     blkcnt;
        int                     valuelen;
        int                     nmap;
        int                     error;
        int                     offset = 0;

        trace_xfs_attr_rmtval_set(args);

        /*
         * Find a "hole" in the attribute address space large enough for
         * us to drop the new attribute's value into. Because CRC enable
         * attributes have headers, we can't just do a straight byte to FSB
         * conversion and have to take the header space into account.
         */
        blkcnt = xfs_attr3_rmt_blocks(mp, args->rmtvaluelen);
        error = xfs_bmap_first_unused(args->trans, args->dp, blkcnt, &lfileoff,
                                                   XFS_ATTR_FORK);
        if (error)
                return error;

        args->rmtblkno = lblkno = (xfs_dablk_t)lfileoff;
        args->rmtblkcnt = blkcnt;

        /*
         * Roll through the "value", allocating blocks on disk as required.
         */
        while (blkcnt > 0) {
                /*
                 * Allocate a single extent, up to the size of the value.
                 *
                 * Note that we have to consider this a data allocation as we
                 * write the remote attribute without logging the contents.
                 * Hence we must ensure that we aren't using blocks that are on
                 * the busy list so that we don't overwrite blocks which have
                 * recently been freed but their transactions are not yet
                 * committed to disk. If we overwrite the contents of a busy
                 * extent and then crash then the block may not contain the
                 * correct metadata after log recovery occurs.
                 */
                xfs_defer_init(args->dfops, args->firstblock);
                nmap = 1;
                error = xfs_bmapi_write(args->trans, dp, (xfs_fileoff_t)lblkno,
                                  blkcnt, XFS_BMAPI_ATTRFORK, args->firstblock,
                                  args->total, &map, &nmap, args->dfops);
                if (!error)
                        error = xfs_defer_finish(&args->trans, args->dfops, dp);
                if (error) {
                        args->trans = NULL;
                        xfs_defer_cancel(args->dfops);
                        return error;
                }

                ASSERT(nmap == 1);
                ASSERT((map.br_startblock != DELAYSTARTBLOCK) &&
                       (map.br_startblock != HOLESTARTBLOCK));
                lblkno += map.br_blockcount;
                blkcnt -= map.br_blockcount;

                /*
                 * Start the next trans in the chain.
                 */
                error = xfs_trans_roll(&args->trans, dp);
                if (error)
                        return error;
        }

        /*
         * Roll through the "value", copying the attribute value to the
         * already-allocated blocks.  Blocks are written synchronously
         * so that we can know they are all on disk before we turn off
         * the INCOMPLETE flag.
         */
        lblkno = args->rmtblkno;
        blkcnt = args->rmtblkcnt;
        valuelen = args->rmtvaluelen;
        while (valuelen > 0) {
                struct xfs_buf  *bp;
                xfs_daddr_t     dblkno;
                int             dblkcnt;

                ASSERT(blkcnt > 0);

                xfs_defer_init(args->dfops, args->firstblock);
                nmap = 1;
                error = xfs_bmapi_read(dp, (xfs_fileoff_t)lblkno,
                                       blkcnt, &map, &nmap,
                                       XFS_BMAPI_ATTRFORK);
                if (error)
                        return error;
                ASSERT(nmap == 1);
                ASSERT((map.br_startblock != DELAYSTARTBLOCK) &&
                       (map.br_startblock != HOLESTARTBLOCK));

                dblkno = XFS_FSB_TO_DADDR(mp, map.br_startblock),
                dblkcnt = XFS_FSB_TO_BB(mp, map.br_blockcount);

                bp = xfs_buf_get(mp->m_ddev_targp, dblkno, dblkcnt, 0);
                if (!bp)
                        return -ENOMEM;
                bp->b_ops = &xfs_attr3_rmt_buf_ops;

                xfs_attr_rmtval_copyin(mp, bp, args->dp->i_ino, &offset,
                                       &valuelen, &src);

                error = xfs_bwrite(bp); /* GROT: NOTE: synchronous write */
                xfs_buf_relse(bp);
                if (error)
                        return error;


                /* roll attribute extent map forwards */
                lblkno += map.br_blockcount;
                blkcnt -= map.br_blockcount;
        }
        ASSERT(valuelen == 0);
        return 0;
}

/*
 * Remove the value associated with an attribute by deleting the
 * out-of-line buffer that it is stored on.
 */
int
xfs_attr_rmtval_remove(
        struct xfs_da_args      *args)
{
        struct xfs_mount        *mp = args->dp->i_mount;
        xfs_dablk_t             lblkno;
        int                     blkcnt;
        int                     error;
        int                     done;

        trace_xfs_attr_rmtval_remove(args);

        /*
         * Roll through the "value", invalidating the attribute value's blocks.
         */
        lblkno = args->rmtblkno;
        blkcnt = args->rmtblkcnt;
        while (blkcnt > 0) {
                struct xfs_bmbt_irec    map;
                struct xfs_buf          *bp;
                xfs_daddr_t             dblkno;
                int                     dblkcnt;
                int                     nmap;

                /*
                 * Try to remember where we decided to put the value.
                 */
                nmap = 1;
                error = xfs_bmapi_read(args->dp, (xfs_fileoff_t)lblkno,
                                       blkcnt, &map, &nmap, XFS_BMAPI_ATTRFORK);
                if (error)
                        return error;
                ASSERT(nmap == 1);
                ASSERT((map.br_startblock != DELAYSTARTBLOCK) &&
                       (map.br_startblock != HOLESTARTBLOCK));

                dblkno = XFS_FSB_TO_DADDR(mp, map.br_startblock),
                dblkcnt = XFS_FSB_TO_BB(mp, map.br_blockcount);

                /*
                 * If the "remote" value is in the cache, remove it.
                 */
                bp = xfs_incore(mp->m_ddev_targp, dblkno, dblkcnt, XBF_TRYLOCK);
                if (bp) {
                        xfs_buf_stale(bp);
                        xfs_buf_relse(bp);
                        bp = NULL;
                }

                lblkno += map.br_blockcount;
                blkcnt -= map.br_blockcount;
        }

        /*
         * Keep de-allocating extents until the remote-value region is gone.
         */
        lblkno = args->rmtblkno;
        blkcnt = args->rmtblkcnt;
        done = 0;
        while (!done) {
                xfs_defer_init(args->dfops, args->firstblock);
                error = xfs_bunmapi(args->trans, args->dp, lblkno, blkcnt,
                                    XFS_BMAPI_ATTRFORK, 1, args->firstblock,
                                    args->dfops, &done);
                if (!error)
                        error = xfs_defer_finish(&args->trans, args->dfops,
                                                args->dp);
                if (error) {
                        args->trans = NULL;
                        xfs_defer_cancel(args->dfops);
                        return error;
                }

                /*
                 * Close out trans and start the next one in the chain.
                 */
                error = xfs_trans_roll(&args->trans, args->dp);
                if (error)
                        return error;
        }
        return 0;
}