Merge tag 'for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso...

[mirror_ubuntu-artful-kernel.git] / fs / xfs / xfs_symlink.c

/*
 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
 * Copyright (c) 2012-2013 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_shared.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_dir2.h"
#include "xfs_inode.h"
#include "xfs_ialloc.h"
#include "xfs_alloc.h"
#include "xfs_bmap.h"
#include "xfs_bmap_btree.h"
#include "xfs_bmap_util.h"
#include "xfs_error.h"
#include "xfs_quota.h"
#include "xfs_trans_space.h"
#include "xfs_trace.h"
#include "xfs_symlink.h"
#include "xfs_trans.h"
#include "xfs_log.h"

/* ----- Kernel only functions below ----- */
STATIC int
xfs_readlink_bmap(
        struct xfs_inode        *ip,
        char                    *link)
{
        struct xfs_mount        *mp = ip->i_mount;
        struct xfs_bmbt_irec    mval[XFS_SYMLINK_MAPS];
        struct xfs_buf          *bp;
        xfs_daddr_t             d;
        char                    *cur_chunk;
        int                     pathlen = ip->i_d.di_size;
        int                     nmaps = XFS_SYMLINK_MAPS;
        int                     byte_cnt;
        int                     n;
        int                     error = 0;
        int                     fsblocks = 0;
        int                     offset;

        fsblocks = xfs_symlink_blocks(mp, pathlen);
        error = xfs_bmapi_read(ip, 0, fsblocks, mval, &nmaps, 0);
        if (error)
                goto out;

        offset = 0;
        for (n = 0; n < nmaps; n++) {
                d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
                byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);

                bp = xfs_buf_read(mp->m_ddev_targp, d, BTOBB(byte_cnt), 0,
                                  &xfs_symlink_buf_ops);
                if (!bp)
                        return -ENOMEM;
                error = bp->b_error;
                if (error) {
                        xfs_buf_ioerror_alert(bp, __func__);
                        xfs_buf_relse(bp);

                        /* bad CRC means corrupted metadata */
                        if (error == -EFSBADCRC)
                                error = -EFSCORRUPTED;
                        goto out;
                }
                byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
                if (pathlen < byte_cnt)
                        byte_cnt = pathlen;

                cur_chunk = bp->b_addr;
                if (xfs_sb_version_hascrc(&mp->m_sb)) {
                        if (!xfs_symlink_hdr_ok(ip->i_ino, offset,
                                                        byte_cnt, bp)) {
                                error = -EFSCORRUPTED;
                                xfs_alert(mp,
"symlink header does not match required off/len/owner (0x%x/Ox%x,0x%llx)",
                                        offset, byte_cnt, ip->i_ino);
                                xfs_buf_relse(bp);
                                goto out;

                        }

                        cur_chunk += sizeof(struct xfs_dsymlink_hdr);
                }

                memcpy(link + offset, bp->b_addr, byte_cnt);

                pathlen -= byte_cnt;
                offset += byte_cnt;

                xfs_buf_relse(bp);
        }
        ASSERT(pathlen == 0);

        link[ip->i_d.di_size] = '\0';
        error = 0;

 out:
        return error;
}

int
xfs_readlink(
        struct xfs_inode *ip,
        char            *link)
{
        struct xfs_mount *mp = ip->i_mount;
        xfs_fsize_t     pathlen;
        int             error = 0;

        trace_xfs_readlink(ip);

        if (XFS_FORCED_SHUTDOWN(mp))
                return -EIO;

        xfs_ilock(ip, XFS_ILOCK_SHARED);

        pathlen = ip->i_d.di_size;
        if (!pathlen)
                goto out;

        if (pathlen < 0 || pathlen > MAXPATHLEN) {
                xfs_alert(mp, "%s: inode (%llu) bad symlink length (%lld)",
                         __func__, (unsigned long long) ip->i_ino,
                         (long long) pathlen);
                ASSERT(0);
                error = -EFSCORRUPTED;
                goto out;
        }


        if (ip->i_df.if_flags & XFS_IFINLINE) {
                memcpy(link, ip->i_df.if_u1.if_data, pathlen);
                link[pathlen] = '\0';
        } else {
                error = xfs_readlink_bmap(ip, link);
        }

 out:
        xfs_iunlock(ip, XFS_ILOCK_SHARED);
        return error;
}

int
xfs_symlink(
        struct xfs_inode        *dp,
        struct xfs_name         *link_name,
        const char              *target_path,
        umode_t                 mode,
        struct xfs_inode        **ipp)
{
        struct xfs_mount        *mp = dp->i_mount;
        struct xfs_trans        *tp = NULL;
        struct xfs_inode        *ip = NULL;
        int                     error = 0;
        int                     pathlen;
        struct xfs_bmap_free    free_list;
        xfs_fsblock_t           first_block;
        bool                    unlock_dp_on_error = false;
        uint                    cancel_flags;
        int                     committed;
        xfs_fileoff_t           first_fsb;
        xfs_filblks_t           fs_blocks;
        int                     nmaps;
        struct xfs_bmbt_irec    mval[XFS_SYMLINK_MAPS];
        xfs_daddr_t             d;
        const char              *cur_chunk;
        int                     byte_cnt;
        int                     n;
        xfs_buf_t               *bp;
        prid_t                  prid;
        struct xfs_dquot        *udqp = NULL;
        struct xfs_dquot        *gdqp = NULL;
        struct xfs_dquot        *pdqp = NULL;
        uint                    resblks;

        *ipp = NULL;

        trace_xfs_symlink(dp, link_name);

        if (XFS_FORCED_SHUTDOWN(mp))
                return -EIO;

        /*
         * Check component lengths of the target path name.
         */
        pathlen = strlen(target_path);
        if (pathlen >= MAXPATHLEN)      /* total string too long */
                return -ENAMETOOLONG;

        udqp = gdqp = NULL;
        prid = xfs_get_initial_prid(dp);

        /*
         * Make sure that we have allocated dquot(s) on disk.
         */
        error = xfs_qm_vop_dqalloc(dp,
                        xfs_kuid_to_uid(current_fsuid()),
                        xfs_kgid_to_gid(current_fsgid()), prid,
                        XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
                        &udqp, &gdqp, &pdqp);
        if (error)
                return error;

        tp = xfs_trans_alloc(mp, XFS_TRANS_SYMLINK);
        cancel_flags = XFS_TRANS_RELEASE_LOG_RES;
        /*
         * The symlink will fit into the inode data fork?
         * There can't be any attributes so we get the whole variable part.
         */
        if (pathlen <= XFS_LITINO(mp, dp->i_d.di_version))
                fs_blocks = 0;
        else
                fs_blocks = xfs_symlink_blocks(mp, pathlen);
        resblks = XFS_SYMLINK_SPACE_RES(mp, link_name->len, fs_blocks);
        error = xfs_trans_reserve(tp, &M_RES(mp)->tr_symlink, resblks, 0);
        if (error == -ENOSPC && fs_blocks == 0) {
                resblks = 0;
                error = xfs_trans_reserve(tp, &M_RES(mp)->tr_symlink, 0, 0);
        }
        if (error) {
                cancel_flags = 0;
                goto out_trans_cancel;
        }

        xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
        unlock_dp_on_error = true;

        /*
         * Check whether the directory allows new symlinks or not.
         */
        if (dp->i_d.di_flags & XFS_DIFLAG_NOSYMLINKS) {
                error = -EPERM;
                goto out_trans_cancel;
        }

        /*
         * Reserve disk quota : blocks and inode.
         */
        error = xfs_trans_reserve_quota(tp, mp, udqp, gdqp,
                                                pdqp, resblks, 1, 0);
        if (error)
                goto out_trans_cancel;

        /*
         * Check for ability to enter directory entry, if no space reserved.
         */
        if (!resblks) {
                error = xfs_dir_canenter(tp, dp, link_name);
                if (error)
                        goto out_trans_cancel;
        }
        /*
         * Initialize the bmap freelist prior to calling either
         * bmapi or the directory create code.
         */
        xfs_bmap_init(&free_list, &first_block);

        /*
         * Allocate an inode for the symlink.
         */
        error = xfs_dir_ialloc(&tp, dp, S_IFLNK | (mode & ~S_IFMT), 1, 0,
                               prid, resblks > 0, &ip, NULL);
        if (error)
                goto out_trans_cancel;

        /*
         * Now we join the directory inode to the transaction.  We do not do it
         * earlier because xfs_dir_ialloc might commit the previous transaction
         * (and release all the locks).  An error from here on will result in
         * the transaction cancel unlocking dp so don't do it explicitly in the
         * error path.
         */
        xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
        unlock_dp_on_error = false;

        /*
         * Also attach the dquot(s) to it, if applicable.
         */
        xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp);

        if (resblks)
                resblks -= XFS_IALLOC_SPACE_RES(mp);
        /*
         * If the symlink will fit into the inode, write it inline.
         */
        if (pathlen <= XFS_IFORK_DSIZE(ip)) {
                xfs_idata_realloc(ip, pathlen, XFS_DATA_FORK);
                memcpy(ip->i_df.if_u1.if_data, target_path, pathlen);
                ip->i_d.di_size = pathlen;

                /*
                 * The inode was initially created in extent format.
                 */
                ip->i_df.if_flags &= ~(XFS_IFEXTENTS | XFS_IFBROOT);
                ip->i_df.if_flags |= XFS_IFINLINE;

                ip->i_d.di_format = XFS_DINODE_FMT_LOCAL;
                xfs_trans_log_inode(tp, ip, XFS_ILOG_DDATA | XFS_ILOG_CORE);

        } else {
                int     offset;

                first_fsb = 0;
                nmaps = XFS_SYMLINK_MAPS;

                error = xfs_bmapi_write(tp, ip, first_fsb, fs_blocks,
                                  XFS_BMAPI_METADATA, &first_block, resblks,
                                  mval, &nmaps, &free_list);
                if (error)
                        goto out_bmap_cancel;

                if (resblks)
                        resblks -= fs_blocks;
                ip->i_d.di_size = pathlen;
                xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);

                cur_chunk = target_path;
                offset = 0;
                for (n = 0; n < nmaps; n++) {
                        char    *buf;

                        d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
                        byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
                        bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, d,
                                               BTOBB(byte_cnt), 0);
                        if (!bp) {
                                error = -ENOMEM;
                                goto out_bmap_cancel;
                        }
                        bp->b_ops = &xfs_symlink_buf_ops;

                        byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
                        byte_cnt = min(byte_cnt, pathlen);

                        buf = bp->b_addr;
                        buf += xfs_symlink_hdr_set(mp, ip->i_ino, offset,
                                                   byte_cnt, bp);

                        memcpy(buf, cur_chunk, byte_cnt);

                        cur_chunk += byte_cnt;
                        pathlen -= byte_cnt;
                        offset += byte_cnt;

                        xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF);
                        xfs_trans_log_buf(tp, bp, 0, (buf + byte_cnt - 1) -
                                                        (char *)bp->b_addr);
                }
                ASSERT(pathlen == 0);
        }

        /*
         * Create the directory entry for the symlink.
         */
        error = xfs_dir_createname(tp, dp, link_name, ip->i_ino,
                                        &first_block, &free_list, resblks);
        if (error)
                goto out_bmap_cancel;
        xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
        xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);

        /*
         * If this is a synchronous mount, make sure that the
         * symlink transaction goes to disk before returning to
         * the user.
         */
        if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC)) {
                xfs_trans_set_sync(tp);
        }

        error = xfs_bmap_finish(&tp, &free_list, &committed);
        if (error)
                goto out_bmap_cancel;

        error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
        if (error)
                goto out_release_inode;

        xfs_qm_dqrele(udqp);
        xfs_qm_dqrele(gdqp);
        xfs_qm_dqrele(pdqp);

        *ipp = ip;
        return 0;

out_bmap_cancel:
        xfs_bmap_cancel(&free_list);
        cancel_flags |= XFS_TRANS_ABORT;
out_trans_cancel:
        xfs_trans_cancel(tp, cancel_flags);
out_release_inode:
        /*
         * Wait until after the current transaction is aborted to finish the
         * setup of the inode and release the inode.  This prevents recursive
         * transactions and deadlocks from xfs_inactive.
         */
        if (ip) {
                xfs_finish_inode_setup(ip);
                IRELE(ip);
        }

        xfs_qm_dqrele(udqp);
        xfs_qm_dqrele(gdqp);
        xfs_qm_dqrele(pdqp);

        if (unlock_dp_on_error)
                xfs_iunlock(dp, XFS_ILOCK_EXCL);
        return error;
}

/*
 * Free a symlink that has blocks associated with it.
 */
STATIC int
xfs_inactive_symlink_rmt(
        struct xfs_inode *ip)
{
        xfs_buf_t       *bp;
        int             committed;
        int             done;
        int             error;
        xfs_fsblock_t   first_block;
        xfs_bmap_free_t free_list;
        int             i;
        xfs_mount_t     *mp;
        xfs_bmbt_irec_t mval[XFS_SYMLINK_MAPS];
        int             nmaps;
        int             size;
        xfs_trans_t     *tp;

        mp = ip->i_mount;
        ASSERT(ip->i_df.if_flags & XFS_IFEXTENTS);
        /*
         * We're freeing a symlink that has some
         * blocks allocated to it.  Free the
         * blocks here.  We know that we've got
         * either 1 or 2 extents and that we can
         * free them all in one bunmapi call.
         */
        ASSERT(ip->i_d.di_nextents > 0 && ip->i_d.di_nextents <= 2);

        tp = xfs_trans_alloc(mp, XFS_TRANS_INACTIVE);
        error = xfs_trans_reserve(tp, &M_RES(mp)->tr_itruncate, 0, 0);
        if (error) {
                xfs_trans_cancel(tp, 0);
                return error;
        }

        xfs_ilock(ip, XFS_ILOCK_EXCL);
        xfs_trans_ijoin(tp, ip, 0);

        /*
         * Lock the inode, fix the size, and join it to the transaction.
         * Hold it so in the normal path, we still have it locked for
         * the second transaction.  In the error paths we need it
         * held so the cancel won't rele it, see below.
         */
        size = (int)ip->i_d.di_size;
        ip->i_d.di_size = 0;
        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
        /*
         * Find the block(s) so we can inval and unmap them.
         */
        done = 0;
        xfs_bmap_init(&free_list, &first_block);
        nmaps = ARRAY_SIZE(mval);
        error = xfs_bmapi_read(ip, 0, xfs_symlink_blocks(mp, size),
                                mval, &nmaps, 0);
        if (error)
                goto error_trans_cancel;
        /*
         * Invalidate the block(s). No validation is done.
         */
        for (i = 0; i < nmaps; i++) {
                bp = xfs_trans_get_buf(tp, mp->m_ddev_targp,
                        XFS_FSB_TO_DADDR(mp, mval[i].br_startblock),
                        XFS_FSB_TO_BB(mp, mval[i].br_blockcount), 0);
                if (!bp) {
                        error = -ENOMEM;
                        goto error_bmap_cancel;
                }
                xfs_trans_binval(tp, bp);
        }
        /*
         * Unmap the dead block(s) to the free_list.
         */
        error = xfs_bunmapi(tp, ip, 0, size, XFS_BMAPI_METADATA, nmaps,
                            &first_block, &free_list, &done);
        if (error)
                goto error_bmap_cancel;
        ASSERT(done);
        /*
         * Commit the first transaction.  This logs the EFI and the inode.
         */
        error = xfs_bmap_finish(&tp, &free_list, &committed);
        if (error)
                goto error_bmap_cancel;
        /*
         * The transaction must have been committed, since there were
         * actually extents freed by xfs_bunmapi.  See xfs_bmap_finish.
         * The new tp has the extent freeing and EFDs.
         */
        ASSERT(committed);
        /*
         * The first xact was committed, so add the inode to the new one.
         * Mark it dirty so it will be logged and moved forward in the log as
         * part of every commit.
         */
        xfs_trans_ijoin(tp, ip, 0);
        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
        /*
         * Commit the transaction containing extent freeing and EFDs.
         */
        error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
        if (error) {
                ASSERT(XFS_FORCED_SHUTDOWN(mp));
                goto error_unlock;
        }

        /*
         * Remove the memory for extent descriptions (just bookkeeping).
         */
        if (ip->i_df.if_bytes)
                xfs_idata_realloc(ip, -ip->i_df.if_bytes, XFS_DATA_FORK);
        ASSERT(ip->i_df.if_bytes == 0);

        xfs_iunlock(ip, XFS_ILOCK_EXCL);
        return 0;

error_bmap_cancel:
        xfs_bmap_cancel(&free_list);
error_trans_cancel:
        xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
error_unlock:
        xfs_iunlock(ip, XFS_ILOCK_EXCL);
        return error;
}

/*
 * xfs_inactive_symlink - free a symlink
 */
int
xfs_inactive_symlink(
        struct xfs_inode        *ip)
{
        struct xfs_mount        *mp = ip->i_mount;
        int                     pathlen;

        trace_xfs_inactive_symlink(ip);

        if (XFS_FORCED_SHUTDOWN(mp))
                return -EIO;

        xfs_ilock(ip, XFS_ILOCK_EXCL);

        /*
         * Zero length symlinks _can_ exist.
         */
        pathlen = (int)ip->i_d.di_size;
        if (!pathlen) {
                xfs_iunlock(ip, XFS_ILOCK_EXCL);
                return 0;
        }

        if (pathlen < 0 || pathlen > MAXPATHLEN) {
                xfs_alert(mp, "%s: inode (0x%llx) bad symlink length (%d)",
                         __func__, (unsigned long long)ip->i_ino, pathlen);
                xfs_iunlock(ip, XFS_ILOCK_EXCL);
                ASSERT(0);
                return -EFSCORRUPTED;
        }

        if (ip->i_df.if_flags & XFS_IFINLINE) {
                if (ip->i_df.if_bytes > 0) 
                        xfs_idata_realloc(ip, -(ip->i_df.if_bytes),
                                          XFS_DATA_FORK);
                xfs_iunlock(ip, XFS_ILOCK_EXCL);
                ASSERT(ip->i_df.if_bytes == 0);
                return 0;
        }

        xfs_iunlock(ip, XFS_ILOCK_EXCL);

        /* remove the remote symlink */
        return xfs_inactive_symlink_rmt(ip);
}