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Re: [PATCH v4 2/10] xfs: Add support FALLOC_FL_INSERT_RANGE for fallocat

To: Namjae Jeon <namjae.jeon@xxxxxxxxxxx>
Subject: Re: [PATCH v4 2/10] xfs: Add support FALLOC_FL_INSERT_RANGE for fallocate
From: Brian Foster <bfoster@xxxxxxxxxx>
Date: Fri, 30 May 2014 10:05:52 -0400
Cc: Dave Chinner <david@xxxxxxxxxxxxx>, xfs@xxxxxxxxxxx, linux-fsdevel@xxxxxxxxxxxxxxx, Ashish Sangwan <a.sangwan@xxxxxxxxxxx>
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <001e01cf7b0f$ba43dfd0$2ecb9f70$@samsung.com>
References: <001e01cf7b0f$ba43dfd0$2ecb9f70$@samsung.com>
User-agent: Mutt/1.5.21 (2010-09-15)
On Thu, May 29, 2014 at 04:29:29PM +0900, Namjae Jeon wrote:
> This patch implements fallocate's FALLOC_FL_INSERT_RANGE for XFS.
> 
> 1) Make sure that both offset and len are block size aligned.
> 2) Update the i_size of inode by len bytes.
> 3) Compute the file's logical block number against offset. If the computed
>    block number is not the starting block of the extent, split the extent
>    such that the block number is the starting block of the extent.
> 4) Shift all the extents which are lying bewteen [offset, last allocated 
> extent]
>    towards right by len bytes. This step will make a hole of len bytes
>    at offset.
> 5) Allocate unwritten extents for the hole created in step 4.
> 
> Signed-off-by: Namjae Jeon <namjae.jeon@xxxxxxxxxxx>
> Signed-off-by: Ashish Sangwan <a.sangwan@xxxxxxxxxxx>
> Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
> ---
> 
> Changelog
> v4:
>  - set cur->bc_private.b.allocated to zero before calling 
> xfs_btree_del_cursor.
> 

Other issues not withstanding (sounds like Mark still has a lingering,
potential corruption case), this fixes the warnings I was seeing. I ran
through an xfstest cycle without problem. Thanks for fixing this.

The cursor allocated flag appears to be used to carry bmbt block
allocations over to delayed allocation extent conversions (such that
these allocations are accounted from previous delalloc extent index
block reservations). This is all within the bmbt code, so clearing the
flag seems reasonable as well.

Though I wonder why it falls on the caller to clear the flag as opposed
to fixing up the flag automatically when it becomes accounted for. I
guess that would enable a warning with semantics of "something might
have been unaccounted for" vs. "somebody forgot to reset a flag." That
said, it's likely there are circumstances involved with this mechanism
that I'm not yet familiar with. ;)

Brian

> v3:
>  - remove XFS_TRANS_RESERVE and assert.
>  - update the comment of blockcount calculation.
>  - use 'if(blockcount)' instead of 'if (got.br_blockcount < blockcount)'.
>  - move insert_file_space() calling under xfs_setattr_size to avoid code 
> duplicate.
> 
> v2:
>  - remove reserved enable.
>  - add xfs_qm_dqattach.
>  - reset blockcount in xfs_bmap_shift_extents_right.
>  - update i_size to avoid data loss before insert_file_space() is called.
>  - use in-memory extent array size that delayed allocation extents.
> 
>  fs/xfs/xfs_bmap.c      | 379 
> ++++++++++++++++++++++++++++++++++++++++++++++++-
>  fs/xfs/xfs_bmap.h      |   9 +-
>  fs/xfs/xfs_bmap_util.c | 128 ++++++++++++++++-
>  fs/xfs/xfs_bmap_util.h |   2 +
>  fs/xfs/xfs_file.c      |  38 ++++-
>  fs/xfs/xfs_trace.h     |   1 +
>  6 files changed, 552 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/xfs/xfs_bmap.c b/fs/xfs/xfs_bmap.c
> index 1ff0da6..a6d4e8d 100644
> --- a/fs/xfs/xfs_bmap.c
> +++ b/fs/xfs/xfs_bmap.c
> @@ -5419,7 +5419,7 @@ error0:
>   * into, this will be considered invalid operation and we abort immediately.
>   */
>  int
> -xfs_bmap_shift_extents(
> +xfs_bmap_shift_extents_left(
>       struct xfs_trans        *tp,
>       struct xfs_inode        *ip,
>       int                     *done,
> @@ -5449,7 +5449,7 @@ xfs_bmap_shift_extents(
>           (XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_EXTENTS &&
>            XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_BTREE),
>            mp, XFS_ERRTAG_BMAPIFORMAT, XFS_RANDOM_BMAPIFORMAT))) {
> -             XFS_ERROR_REPORT("xfs_bmap_shift_extents",
> +             XFS_ERROR_REPORT("xfs_bmap_shift_extents_left",
>                                XFS_ERRLEVEL_LOW, mp);
>               return XFS_ERROR(EFSCORRUPTED);
>       }
> @@ -5606,3 +5606,378 @@ del_cursor:
>       xfs_trans_log_inode(tp, ip, logflags);
>       return error;
>  }
> +
> +/*
> + * Splits an extent into two extents at split_fsb block that it is
> + * the first block of the current_ext. @current_ext is a target extent
> + * to be splitted. @split_fsb is a block where the extents is spliited.
> + * If split_fsb lies in a hole or the first block of extents, just return 0.
> + */
> +STATIC int
> +xfs_bmap_split_extent_at(
> +     struct xfs_trans        *tp,
> +     struct xfs_inode        *ip,
> +     xfs_fileoff_t           split_fsb,
> +     xfs_extnum_t            *current_ext,
> +     xfs_fsblock_t           *firstfsb,
> +     struct xfs_bmap_free    *free_list)
> +{
> +     int                             whichfork = XFS_DATA_FORK;
> +     struct xfs_btree_cur            *cur;
> +     struct xfs_bmbt_rec_host        *gotp;
> +     struct xfs_bmbt_irec            got;
> +     struct xfs_bmbt_irec            new; /* splitted extent */
> +     struct xfs_mount                *mp = ip->i_mount;
> +     struct xfs_ifork                *ifp;
> +     xfs_fsblock_t                   gotblkcnt; /* new block count for got */
> +     int                             error = 0;
> +     int                             logflags;
> +     int                             i = 0;
> +
> +     if (unlikely(XFS_TEST_ERROR(
> +         (XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_EXTENTS &&
> +          XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_BTREE),
> +          mp, XFS_ERRTAG_BMAPIFORMAT, XFS_RANDOM_BMAPIFORMAT))) {
> +             XFS_ERROR_REPORT("xfs_bmap_split_extent_at",
> +                              XFS_ERRLEVEL_LOW, mp);
> +             return XFS_ERROR(EFSCORRUPTED);
> +     }
> +
> +     if (XFS_FORCED_SHUTDOWN(mp))
> +             return XFS_ERROR(EIO);
> +
> +     ASSERT(current_ext != NULL);
> +
> +     ifp = XFS_IFORK_PTR(ip, whichfork);
> +     if (!(ifp->if_flags & XFS_IFEXTENTS)) {
> +             /* Read in all the extents */
> +             error = xfs_iread_extents(tp, ip, whichfork);
> +             if (error)
> +                     return error;
> +     }
> +
> +     gotp = xfs_iext_bno_to_ext(ifp, split_fsb, current_ext);
> +     /*
> +      * gotp can be null in 2 cases: 1) if there are no extents
> +      * or 2) split_fsb lies in a hole beyond which there are
> +      * no extents. Either way, we are done.
> +      */
> +     if (!gotp)
> +             return 0;
> +
> +     xfs_bmbt_get_all(gotp, &got);
> +
> +     /*
> +      * Check split_fsb lies in a hole or the start boundary offset
> +      * of the extent.
> +      */
> +     if (got.br_startoff >= split_fsb)
> +             return 0;
> +
> +     gotblkcnt = split_fsb - got.br_startoff;
> +     new.br_startoff = split_fsb;
> +     new.br_startblock = got.br_startblock + gotblkcnt;
> +     new.br_blockcount = got.br_blockcount - gotblkcnt;
> +     new.br_state = got.br_state;
> +
> +     /* We are going to change core inode */
> +     logflags = XFS_ILOG_CORE;
> +
> +     if (ifp->if_flags & XFS_IFBROOT) {
> +             cur = xfs_bmbt_init_cursor(mp, tp, ip, whichfork);
> +             cur->bc_private.b.firstblock = *firstfsb;
> +             cur->bc_private.b.flist = free_list;
> +             cur->bc_private.b.flags = 0;
> +     } else {
> +             cur = NULL;
> +             logflags |= XFS_ILOG_DEXT;
> +     }
> +
> +     if (cur) {
> +             error = xfs_bmbt_lookup_eq(cur, got.br_startoff,
> +                                        got.br_startblock,
> +                                        got.br_blockcount,
> +                                        &i);
> +             if (error)
> +                     goto del_cursor;
> +             XFS_WANT_CORRUPTED_GOTO(i == 1, del_cursor);
> +     }
> +
> +     xfs_bmbt_set_blockcount(gotp, gotblkcnt);
> +     got.br_blockcount = gotblkcnt;
> +     if (cur) {
> +             error = xfs_bmbt_update(cur, got.br_startoff,
> +                                     got.br_startblock,
> +                                     got.br_blockcount,
> +                                     got.br_state);
> +             if (error)
> +                     goto del_cursor;
> +     }
> +
> +     /* Add new extent */
> +     (*current_ext)++;
> +     xfs_iext_insert(ip, *current_ext, 1, &new, 0);
> +     XFS_IFORK_NEXT_SET(ip, whichfork,
> +             XFS_IFORK_NEXTENTS(ip, whichfork) + 1);
> +
> +     if (cur) {
> +             error = xfs_bmbt_lookup_eq(cur, new.br_startoff,
> +                                        new.br_startblock, new.br_blockcount,
> +                                        &i);
> +             if (error)
> +                     goto del_cursor;
> +             XFS_WANT_CORRUPTED_GOTO(i == 0, del_cursor);
> +             cur->bc_rec.b.br_state = new.br_state;
> +
> +             error = xfs_btree_insert(cur, &i);
> +             if (error)
> +                     goto del_cursor;
> +             XFS_WANT_CORRUPTED_GOTO(i == 1, del_cursor);
> +     }
> +
> +     /*
> +      * Convert to a btree if necessary.
> +      */
> +     if (xfs_bmap_needs_btree(ip, whichfork)) {
> +             int tmp_logflags; /* partial log flag return val */
> +
> +             ASSERT(cur == NULL);
> +             error = xfs_bmap_extents_to_btree(tp, ip, firstfsb, free_list,
> +                             &cur, 0, &tmp_logflags, whichfork);
> +             logflags |= tmp_logflags;
> +     }
> +
> +del_cursor:
> +     if (cur) {
> +             cur->bc_private.b.allocated = 0;
> +             xfs_btree_del_cursor(cur,
> +                     error ? XFS_BTREE_ERROR : XFS_BTREE_NOERROR);
> +     }
> +     xfs_trans_log_inode(tp, ip, logflags);
> +     return error;
> +}
> +
> +int
> +xfs_bmap_split_extent(
> +     struct xfs_inode        *ip,
> +     xfs_fileoff_t           split_fsb,
> +     xfs_extnum_t            *split_ext)
> +{
> +     struct xfs_mount        *mp = ip->i_mount;
> +     struct xfs_trans        *tp;
> +     struct xfs_bmap_free    free_list;
> +     xfs_fsblock_t           firstfsb;
> +     int                     committed;
> +     int                     error;
> +
> +     tp = xfs_trans_alloc(mp, XFS_TRANS_DIOSTRAT);
> +     error = xfs_trans_reserve(tp, &M_RES(mp)->tr_write,
> +                     XFS_DIOSTRAT_SPACE_RES(mp, 0), 0);
> +
> +     if (error) {
> +             /*
> +              * Free the transaction structure.
> +              */
> +             xfs_trans_cancel(tp, 0);
> +             return error;
> +     }
> +
> +     xfs_ilock(ip, XFS_ILOCK_EXCL);
> +     error = xfs_trans_reserve_quota(tp, mp, ip->i_udquot,
> +                     ip->i_gdquot, ip->i_pdquot,
> +                     XFS_DIOSTRAT_SPACE_RES(mp, 0), 0,
> +                     XFS_QMOPT_RES_REGBLKS);
> +     if (error)
> +             goto error1;
> +
> +     xfs_trans_ijoin(tp, ip, 0);
> +     xfs_bmap_init(&free_list, &firstfsb);
> +
> +     error = xfs_bmap_split_extent_at(tp, ip, split_fsb, split_ext,
> +                                      &firstfsb, &free_list);
> +     if (error)
> +             goto error0;
> +
> +     error = xfs_bmap_finish(&tp, &free_list, &committed);
> +     if (error)
> +             goto error0;
> +
> +     error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
> +     xfs_iunlock(ip, XFS_ILOCK_EXCL);
> +
> +     return error;
> +error0:
> +     xfs_bmap_cancel(&free_list);
> +error1:
> +     xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
> +     xfs_iunlock(ip, XFS_ILOCK_EXCL);
> +     return error;
> +}
> +
> +/*
> + * Shift extent records to the right to make a hole.
> + * The maximum number of extents to be shifted in a single operation
> + * is @num_exts, and @current_ext keeps track of the current extent
> + * index we have shifted. @offset_shift_fsb is the length by which each
> + * extent is shifted. @end_ext is the last extent to be shifted.
> + */
> +int
> +xfs_bmap_shift_extents_right(
> +     struct xfs_trans        *tp,
> +     struct xfs_inode        *ip,
> +     int                     *done,
> +     xfs_fileoff_t           offset_shift_fsb,
> +     xfs_extnum_t            *current_ext,
> +     xfs_extnum_t            end_ext,
> +     xfs_fsblock_t           *firstblock,
> +     struct xfs_bmap_free    *flist,
> +     int                     num_exts)
> +{
> +     struct xfs_mount                *mp = ip->i_mount;
> +     struct xfs_btree_cur            *cur;
> +     struct xfs_bmbt_rec_host        *gotp;
> +     struct xfs_bmbt_irec            got;
> +     struct xfs_bmbt_irec            right;
> +     xfs_ifork_t                     *ifp;
> +     xfs_fileoff_t                   startoff;
> +     xfs_filblks_t                   blockcount = 0;
> +     xfs_extnum_t                    last_extent;
> +     int                             error = 0;
> +     int                             i;
> +     int                             whichfork = XFS_DATA_FORK;
> +     int                             logflags;
> +
> +     if (unlikely(XFS_TEST_ERROR(
> +         (XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_EXTENTS &&
> +          XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_BTREE),
> +          mp, XFS_ERRTAG_BMAPIFORMAT, XFS_RANDOM_BMAPIFORMAT))) {
> +             XFS_ERROR_REPORT("xfs_bmap_shift_extents_right",
> +                              XFS_ERRLEVEL_LOW, mp);
> +             return XFS_ERROR(EFSCORRUPTED);
> +     }
> +
> +     if (XFS_FORCED_SHUTDOWN(mp))
> +             return XFS_ERROR(EIO);
> +
> +     ASSERT(current_ext != NULL);
> +
> +     /* We are going to change core inode */
> +     logflags = XFS_ILOG_CORE;
> +     ifp = XFS_IFORK_PTR(ip, whichfork);
> +
> +     if (ifp->if_flags & XFS_IFBROOT) {
> +             cur = xfs_bmbt_init_cursor(mp, tp, ip, whichfork);
> +             cur->bc_private.b.firstblock = *firstblock;
> +             cur->bc_private.b.flist = flist;
> +             cur->bc_private.b.flags = 0;
> +     } else {
> +             cur = NULL;
> +             logflags |= XFS_ILOG_DEXT;
> +     }
> +
> +     /* start shifting extents to right */
> +     while (num_exts-- > 0) {
> +             blockcount = 0;
> +
> +             if (*current_ext < end_ext) {
> +                     *done = 1;
> +                     break;
> +             }
> +
> +             gotp = xfs_iext_get_ext(ifp, *current_ext);
> +             xfs_bmbt_get_all(gotp, &got);
> +             startoff = got.br_startoff + offset_shift_fsb;
> +
> +             /*
> +              * Before shifting extent into hole, make sure that the hole
> +              * is large enough to accomodate the shift. This checking has
> +              * to be performed for all except the last extent.
> +              */
> +             last_extent = (ifp->if_bytes / sizeof(xfs_bmbt_rec_t)) - 1;
> +             if (last_extent != *current_ext) {
> +                     xfs_bmbt_get_all(xfs_iext_get_ext(ifp,
> +                                             *current_ext + 1), &right);
> +                     if (startoff + got.br_blockcount > right.br_startoff) {
> +                             error = XFS_ERROR(EINVAL);
> +                             if (error)
> +                                     goto del_cursor;
> +                     }
> +             }
> +
> +             /* Check if we can merge 2 adjacent extents */
> +             if (last_extent != *current_ext &&
> +                 right.br_startoff == startoff + got.br_blockcount &&
> +                 right.br_startblock ==
> +                             got.br_startblock + got.br_blockcount &&
> +                 right.br_state == got.br_state &&
> +                 right.br_blockcount + got.br_blockcount <= MAXEXTLEN) {
> +
> +                     /*
> +                      * Merge the current extent with the extent to
> +                      * the right. Remove the right extent, calculate
> +                      * a new block count for the current extent to cover
> +                      * the range of both and decrement the number of extents
> +                      * in the fork.
> +                      */
> +                     blockcount = right.br_blockcount + got.br_blockcount;
> +
> +                     if (cur) {
> +                             error = xfs_bmbt_lookup_eq(cur,
> +                                                        right.br_startoff,
> +                                                        right.br_startblock,
> +                                                        right.br_blockcount,
> +                                                        &i);
> +                             if (error)
> +                                     goto del_cursor;
> +                             XFS_WANT_CORRUPTED_GOTO(i == 1, del_cursor);
> +                     }
> +
> +                     xfs_iext_remove(ip, *current_ext + 1, 1, 0);
> +                     if (cur) {
> +                             error = xfs_btree_delete(cur, &i);
> +                             if (error)
> +                                     goto del_cursor;
> +                             XFS_WANT_CORRUPTED_GOTO(i == 1, del_cursor);
> +                     }
> +                     XFS_IFORK_NEXT_SET(ip, whichfork,
> +                                     XFS_IFORK_NEXTENTS(ip, whichfork) - 1);
> +
> +             }
> +
> +             if (cur) {
> +                     error = xfs_bmbt_lookup_eq(cur, got.br_startoff,
> +                                                got.br_startblock,
> +                                                got.br_blockcount,
> +                                                &i);
> +                     if (error)
> +                             goto del_cursor;
> +                     XFS_WANT_CORRUPTED_GOTO(i == 1, del_cursor);
> +             }
> +
> +             if (blockcount) {
> +                     xfs_bmbt_set_blockcount(gotp, blockcount);
> +                     got.br_blockcount = blockcount;
> +             }
> +
> +             xfs_bmbt_set_startoff(gotp, startoff);
> +             got.br_startoff = startoff;
> +
> +             if (cur) {
> +                     error = xfs_bmbt_update(cur, got.br_startoff,
> +                                             got.br_startblock,
> +                                             got.br_blockcount,
> +                                             got.br_state);
> +                     if (error)
> +                             goto del_cursor;
> +             }
> +
> +             (*current_ext)--;
> +     }
> +
> +del_cursor:
> +     if (cur)
> +             xfs_btree_del_cursor(cur,
> +                     error ? XFS_BTREE_ERROR : XFS_BTREE_NOERROR);
> +     xfs_trans_log_inode(tp, ip, logflags);
> +     return error;
> +}
> diff --git a/fs/xfs/xfs_bmap.h b/fs/xfs/xfs_bmap.h
> index 38ba36e..af05899 100644
> --- a/fs/xfs/xfs_bmap.h
> +++ b/fs/xfs/xfs_bmap.h
> @@ -179,10 +179,17 @@ int     xfs_bunmapi(struct xfs_trans *tp, struct 
> xfs_inode *ip,
>  int  xfs_check_nostate_extents(struct xfs_ifork *ifp, xfs_extnum_t idx,
>               xfs_extnum_t num);
>  uint xfs_default_attroffset(struct xfs_inode *ip);
> -int  xfs_bmap_shift_extents(struct xfs_trans *tp, struct xfs_inode *ip,
> +int  xfs_bmap_shift_extents_left(struct xfs_trans *tp, struct xfs_inode *ip,
>               int *done, xfs_fileoff_t start_fsb,
>               xfs_fileoff_t offset_shift_fsb, xfs_extnum_t *current_ext,
>               xfs_fsblock_t *firstblock, struct xfs_bmap_free *flist,
>               int num_exts);
> +int  xfs_bmap_split_extent(struct xfs_inode *ip, xfs_fileoff_t split_offset,
> +             xfs_extnum_t *split_ext);
> +int  xfs_bmap_shift_extents_right(struct xfs_trans *tp, struct xfs_inode *ip,
> +             int *done, xfs_fsblock_t offset_shift_fsb,
> +             xfs_extnum_t *current_ext, xfs_extnum_t end_ext,
> +             xfs_fsblock_t *firstblock, struct xfs_bmap_free *flist,
> +             int num_exts);
>  
>  #endif       /* __XFS_BMAP_H__ */
> diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
> index 057f671..b9511dd 100644
> --- a/fs/xfs/xfs_bmap_util.c
> +++ b/fs/xfs/xfs_bmap_util.c
> @@ -1548,7 +1548,7 @@ xfs_collapse_file_space(
>                * We are using the write transaction in which max 2 bmbt
>                * updates are allowed
>                */
> -             error = xfs_bmap_shift_extents(tp, ip, &done, start_fsb,
> +             error = xfs_bmap_shift_extents_left(tp, ip, &done, start_fsb,
>                                              shift_fsb, &current_ext,
>                                              &first_block, &free_list,
>                                              XFS_BMAP_MAX_SHIFT_EXTENTS);
> @@ -1572,6 +1572,132 @@ out:
>  }
>  
>  /*
> + * xfs_insert_file_space()
> + *   This routine allocate disk space and shift extent for the given file.
> + *   The first thing we do is to sync dirty data and invalidate page cache
> + *   over the region on which insert range is working. And split an extent
> + *   to two extents at given offset by calling xfs_bmap_split_extent.
> + *   And shift all extent records which are laying between [offset,
> + *   last allocated extent] to the right to reserve hole range. Lastly
> + *   allocate an unwritten extent in hole range created by shifting extents.
> + *
> + * RETURNS:
> + *   0 on success
> + *   errno on error
> + *
> + */
> +int
> +xfs_insert_file_space(
> +     struct xfs_inode        *ip,
> +     loff_t                  offset,
> +     loff_t                  len)
> +{
> +     struct xfs_mount        *mp = ip->i_mount;
> +     struct xfs_trans        *tp;
> +     struct xfs_bmap_free    free_list;
> +     xfs_fsblock_t           first_block;
> +     xfs_ifork_t             *ifp;
> +     int                     done = 0;
> +     int                     committed;
> +     int                     error;
> +     uint                    rounding;
> +     xfs_fileoff_t           start_fsb;
> +     xfs_fileoff_t           shift_fsb;
> +     xfs_extnum_t            split_ext;
> +     xfs_extnum_t            current_ext = 0;
> +     xfs_off_t               ioffset;
> +
> +     ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
> +     trace_xfs_insert_file_space(ip);
> +
> +     error = xfs_qm_dqattach(ip, 0);
> +     if (error)
> +             return error;
> +
> +     /* wait for the completion of any pending DIOs */
> +     inode_dio_wait(VFS_I(ip));
> +
> +     rounding = max_t(uint, 1 << mp->m_sb.sb_blocklog, PAGE_CACHE_SIZE);
> +     ioffset = offset & ~(rounding - 1);
> +     error = -filemap_write_and_wait_range(VFS_I(ip)->i_mapping,
> +                     ioffset, -1);
> +     if (error)
> +             return error;
> +
> +     truncate_pagecache_range(VFS_I(ip), ioffset, -1);
> +
> +     start_fsb = XFS_B_TO_FSB(mp, offset);
> +     shift_fsb = XFS_B_TO_FSB(mp, len);
> +
> +     error = xfs_bmap_split_extent(ip, start_fsb, &split_ext);
> +     if (error)
> +             return error;
> +
> +     ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
> +     current_ext = (ifp->if_bytes / sizeof(xfs_bmbt_rec_t)) - 1;
> +     while (!error && !done) {
> +             tp = xfs_trans_alloc(mp, XFS_TRANS_DIOSTRAT);
> +             /*
> +              * We would need to reserve permanent block for transaction.
> +              * This will come into picture when after shifting extent into
> +              * hole we found that adjacent extents can be merged which
> +              * may lead to freeing of a block during record update.
> +              */
> +             error = xfs_trans_reserve(tp, &M_RES(mp)->tr_write,
> +                             XFS_DIOSTRAT_SPACE_RES(mp, 0), 0);
> +             if (error) {
> +                     xfs_trans_cancel(tp, 0);
> +                     break;
> +             }
> +
> +             xfs_ilock(ip, XFS_ILOCK_EXCL);
> +             error = xfs_trans_reserve_quota(tp, mp, ip->i_udquot,
> +                             ip->i_gdquot, ip->i_pdquot,
> +                             XFS_DIOSTRAT_SPACE_RES(mp, 0), 0,
> +                             XFS_QMOPT_RES_REGBLKS);
> +             if (error)
> +                     goto error1;
> +
> +             xfs_trans_ijoin(tp, ip, 0);
> +
> +             xfs_bmap_init(&free_list, &first_block);
> +
> +             /*
> +              * We are using the write transaction in which max 2 bmbt
> +              * updates are allowed
> +              */
> +             error = xfs_bmap_shift_extents_right(tp, ip, &done, shift_fsb,
> +                                             &current_ext, split_ext,
> +                                             &first_block, &free_list,
> +                                             XFS_BMAP_MAX_SHIFT_EXTENTS);
> +             if (error)
> +                     goto error0;
> +
> +             error = xfs_bmap_finish(&tp, &free_list, &committed);
> +             if (error)
> +                     goto error0;
> +
> +             error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
> +             xfs_iunlock(ip, XFS_ILOCK_EXCL);
> +             if (error)
> +                     goto out;
> +     }
> +
> +     /* Add unwritten extent in a hole range. */
> +     error = xfs_alloc_file_space(ip, offset, len, XFS_BMAPI_PREALLOC);
> +
> +out:
> +     return error;
> +
> +error0:
> +     xfs_bmap_cancel(&free_list);
> +error1:
> +     xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
> +     xfs_iunlock(ip, XFS_ILOCK_EXCL);
> +     return error;
> +}
> +
> +/*
>   * We need to check that the format of the data fork in the temporary inode 
> is
>   * valid for the target inode before doing the swap. This is not a problem 
> with
>   * attr1 because of the fixed fork offset, but attr2 has a dynamically sized
> diff --git a/fs/xfs/xfs_bmap_util.h b/fs/xfs/xfs_bmap_util.h
> index 935ed2b..d62ab4b 100644
> --- a/fs/xfs/xfs_bmap_util.h
> +++ b/fs/xfs/xfs_bmap_util.h
> @@ -101,6 +101,8 @@ int       xfs_zero_file_space(struct xfs_inode *ip, 
> xfs_off_t offset,
>                           xfs_off_t len);
>  int  xfs_collapse_file_space(struct xfs_inode *, xfs_off_t offset,
>                               xfs_off_t len);
> +int  xfs_insert_file_space(struct xfs_inode *, xfs_off_t offset,
> +                             xfs_off_t len);
>  
>  /* EOF block manipulation functions */
>  bool xfs_can_free_eofblocks(struct xfs_inode *ip, bool force);
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index 1f66779..f160cd5 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -756,11 +756,13 @@ xfs_file_fallocate(
>       struct xfs_trans        *tp;
>       long                    error;
>       loff_t                  new_size = 0;
> +     int                     do_file_insert = 0;
>  
>       if (!S_ISREG(inode->i_mode))
>               return -EINVAL;
>       if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |
> -                  FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_ZERO_RANGE))
> +                  FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_ZERO_RANGE |
> +                  FALLOC_FL_INSERT_RANGE))
>               return -EOPNOTSUPP;
>  
>       xfs_ilock(ip, XFS_IOLOCK_EXCL);
> @@ -790,6 +792,28 @@ xfs_file_fallocate(
>               error = xfs_collapse_file_space(ip, offset, len);
>               if (error)
>                       goto out_unlock;
> +     } else if (mode & FALLOC_FL_INSERT_RANGE) {
> +             unsigned blksize_mask = (1 << inode->i_blkbits) - 1;
> +
> +             if (offset & blksize_mask || len & blksize_mask) {
> +                     error = -EINVAL;
> +                     goto out_unlock;
> +             }
> +
> +             /* Check for wrap through zero */
> +             if (inode->i_size + len > inode->i_sb->s_maxbytes) {
> +                     error = -EFBIG;
> +                     goto out_unlock;
> +             }
> +
> +             /* Offset should be less than i_size */
> +             if (offset >= i_size_read(inode)) {
> +                     error = -EINVAL;
> +                     goto out_unlock;
> +             }
> +
> +             new_size = i_size_read(inode) + len;
> +             do_file_insert = 1;
>       } else {
>               if (!(mode & FALLOC_FL_KEEP_SIZE) &&
>                   offset + len > i_size_read(inode)) {
> @@ -840,8 +864,20 @@ xfs_file_fallocate(
>               iattr.ia_valid = ATTR_SIZE;
>               iattr.ia_size = new_size;
>               error = xfs_setattr_size(ip, &iattr);
> +             if (error)
> +                     goto out_unlock;
>       }
>  
> +     /*
> +      * Some operations are performed after the inode size is updated. For
> +      * example, insert range expands the address space of the file, shifts
> +      * all subsequent extents over and allocates space into the hole.
> +      * Updating the size first ensures that shifted extents aren't left
> +      * hanging past EOF in the event of a crash or failure.
> +      */
> +     if (do_file_insert)
> +             error = xfs_insert_file_space(ip, offset, len);
> +
>  out_unlock:
>       xfs_iunlock(ip, XFS_IOLOCK_EXCL);
>       return -error;
> diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
> index 152f827..8943c9f 100644
> --- a/fs/xfs/xfs_trace.h
> +++ b/fs/xfs/xfs_trace.h
> @@ -663,6 +663,7 @@ DEFINE_INODE_EVENT(xfs_alloc_file_space);
>  DEFINE_INODE_EVENT(xfs_free_file_space);
>  DEFINE_INODE_EVENT(xfs_zero_file_space);
>  DEFINE_INODE_EVENT(xfs_collapse_file_space);
> +DEFINE_INODE_EVENT(xfs_insert_file_space);
>  DEFINE_INODE_EVENT(xfs_readdir);
>  #ifdef CONFIG_XFS_POSIX_ACL
>  DEFINE_INODE_EVENT(xfs_get_acl);
> -- 
> 1.7.11-rc0
> 

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