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Re: [PATCH v7 2/11] xfs: Add support FALLOC_FL_INSERT_RANGE for fallocat

To: Namjae Jeon <namjae.jeon@xxxxxxxxxxx>
Subject: Re: [PATCH v7 2/11] xfs: Add support FALLOC_FL_INSERT_RANGE for fallocate
From: Brian Foster <bfoster@xxxxxxxxxx>
Date: Tue, 6 Jan 2015 11:33:27 -0500
Cc: Dave Chinner <david@xxxxxxxxxxxxx>, "Theodore Ts'o" <tytso@xxxxxxx>, linux-fsdevel@xxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, linux-ext4 <linux-ext4@xxxxxxxxxxxxxxx>, xfs@xxxxxxxxxxx, Ashish Sangwan <a.sangwan@xxxxxxxxxxx>
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <004001d02670$33d2f3c0$9b78db40$@samsung.com>
References: <004001d02670$33d2f3c0$9b78db40$@samsung.com>
User-agent: Mutt/1.5.23 (2014-03-12)
On Fri, Jan 02, 2015 at 06:40:54PM +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.
> 
> Signed-off-by: Namjae Jeon <namjae.jeon@xxxxxxxxxxx>
> Signed-off-by: Ashish Sangwan <a.sangwan@xxxxxxxxxxx>
> Cc: Brian Foster<bfoster@xxxxxxxxxx>
> ---

Hi Namjae,

Just a few small things...

> Changelog
> v7:
>  - Fixed review comments from Brian, important ones are: 
>    a)no need to check for adjacent extent merge
>    b)avoid unnecessary inode logging in case of error.
> 
> v6:
>  - This version is based upon Brian's changes to collapse paths.
>  - Instead of having seperate functions for shifting extents left/right, the
>    current extent shift function is made generic to shift in both directions.
> 
> v5:
>  - remove allocation part.
> 
> v4:
>  - set cur->bc_private.b.allocated to zero before calling 
> xfs_btree_del_cursor.
> 
> 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/libxfs/xfs_bmap.c | 350 
> +++++++++++++++++++++++++++++++++++++++++------
>  fs/xfs/libxfs/xfs_bmap.h |  13 +-
>  fs/xfs/xfs_bmap_util.c   | 126 ++++++++++++-----
>  fs/xfs/xfs_bmap_util.h   |   2 +
>  fs/xfs/xfs_file.c        |  41 +++++-
>  fs/xfs/xfs_trace.h       |   1 +
>  6 files changed, 448 insertions(+), 85 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index b5eb474..a97a893 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
> @@ -5516,50 +5516,78 @@ xfs_bmse_shift_one(
>       int                             *current_ext,
>       struct xfs_bmbt_rec_host        *gotp,
>       struct xfs_btree_cur            *cur,
> -     int                             *logflags)
> +     int                             *logflags,
> +     enum SHIFT_DIRECTION            SHIFT)
>  {
>       struct xfs_ifork                *ifp;
>       xfs_fileoff_t                   startoff;
> -     struct xfs_bmbt_rec_host        *leftp;
> +     struct xfs_bmbt_rec_host        *contp;
>       struct xfs_bmbt_irec            got;
> -     struct xfs_bmbt_irec            left;
> +     struct xfs_bmbt_irec            cont;
>       int                             error;
>       int                             i;
> +     int                             total_extents;
>  
>       ifp = XFS_IFORK_PTR(ip, whichfork);
> +     total_extents = ifp->if_bytes / sizeof(xfs_bmbt_rec_t);
>  
>       xfs_bmbt_get_all(gotp, &got);
> -     startoff = got.br_startoff - offset_shift_fsb;
>  
>       /* delalloc extents should be prevented by caller */
>       XFS_WANT_CORRUPTED_RETURN(!isnullstartblock(got.br_startblock));
>  
> -     /*
> -      * Check for merge if we've got an extent to the left, otherwise make
> -      * sure there's enough room at the start of the file for the shift.
> -      */
> -     if (*current_ext) {
> -             /* grab the left extent and check for a large enough hole */
> -             leftp = xfs_iext_get_ext(ifp, *current_ext - 1);
> -             xfs_bmbt_get_all(leftp, &left);
> +     if (SHIFT == SHIFT_LEFT) {
> +             startoff = got.br_startoff - offset_shift_fsb;
>  
> -             if (startoff < left.br_startoff + left.br_blockcount)
> +             /*
> +              * Check for merge if we've got an extent to the left,
> +              * otherwise make sure there's enough room at the start
> +              * of the file for the shift.
> +              */
> +             if (*current_ext) {
> +                     /*
> +                      * grab the left extent and check for a large
> +                      * enough hole.
> +                      */
> +                     contp = xfs_iext_get_ext(ifp, *current_ext - 1);
> +                     xfs_bmbt_get_all(contp, &cont);
> +
> +                     if (startoff < cont.br_startoff + cont.br_blockcount)
> +                             return -EINVAL;
> +
> +                     /* check whether to merge the extent or shift it down */
> +                     if (xfs_bmse_can_merge(&cont, &got, offset_shift_fsb)) {
> +                             return xfs_bmse_merge(ip, whichfork,
> +                                                   offset_shift_fsb,
> +                                                   *current_ext, gotp, contp,
> +                                                   cur, logflags);
> +                     }
> +             } else if (got.br_startoff < offset_shift_fsb)
>                       return -EINVAL;
> -
> -             /* check whether to merge the extent or shift it down */
> -             if (xfs_bmse_can_merge(&left, &got, offset_shift_fsb)) {
> -                     return xfs_bmse_merge(ip, whichfork, offset_shift_fsb,
> -                                           *current_ext, gotp, leftp, cur,
> -                                           logflags);
> +     } else {
> +             startoff = got.br_startoff + offset_shift_fsb;
> +             /*
> +              * If this is not the last extent in the file, make sure there's
> +              * enough room between current extent and next extent for
> +              * accomodating the shift.

Spelling nit:      accommodating

> +              */
> +             if (*current_ext < (total_extents - 1)) {
> +                     contp = xfs_iext_get_ext(ifp, *current_ext + 1);
> +                     xfs_bmbt_get_all(contp, &cont);
> +                     if (startoff + got.br_blockcount > cont.br_startoff)
> +                             return -EINVAL;
> +                     if (xfs_bmse_can_merge(&got, &cont,  offset_shift_fsb))
> +                             WARN_ON_ONCE(1);

Ok, but a comment before the check would be nice should somebody have to
look up the warning that fires here. E.g.,:

/*
 * Unlike a left shift (which involves a hole punch), a right shift does
 * not modify extent neighbors in any way. We should never find
 * mergeable extents in this scenario. Check anyways and warn if we
 * encounter two extents that could be one.
 */

>               }
> -     } else if (got.br_startoff < offset_shift_fsb)
> -             return -EINVAL;
> -
> +     }
>       /*
>        * Increment the extent index for the next iteration, update the start
>        * offset of the in-core extent and update the btree if applicable.
>        */
> -     (*current_ext)++;
> +     if (SHIFT == SHIFT_LEFT)
> +             (*current_ext)++;
> +     else
> +             (*current_ext)--;
>       xfs_bmbt_set_startoff(gotp, startoff);
>       *logflags |= XFS_ILOG_CORE;
>       if (!cur) {
> @@ -5579,10 +5607,10 @@ xfs_bmse_shift_one(
>  }
>  
>  /*
> - * Shift extent records to the left to cover a hole.
> + * Shift extent records to the left/right to cover/create a hole.
>   *
>   * The maximum number of extents to be shifted in a single operation is
> - * @num_exts. @start_fsb specifies the file offset to start the shift and the
> + * @num_exts. @stop_fsb specifies the file offset at which to stop shift and 
> the
>   * file offset where we've left off is returned in @next_fsb. 
> @offset_shift_fsb
>   * is the length by which each extent is shifted. If there is no hole to 
> shift
>   * the extents into, this will be considered invalid operation and we abort
> @@ -5592,12 +5620,13 @@ int
>  xfs_bmap_shift_extents(
>       struct xfs_trans        *tp,
>       struct xfs_inode        *ip,
> -     xfs_fileoff_t           start_fsb,
> +     xfs_fileoff_t           *next_fsb,
>       xfs_fileoff_t           offset_shift_fsb,
>       int                     *done,
> -     xfs_fileoff_t           *next_fsb,
> +     xfs_fileoff_t           stop_fsb,
>       xfs_fsblock_t           *firstblock,
>       struct xfs_bmap_free    *flist,
> +     enum SHIFT_DIRECTION    SHIFT,
>       int                     num_exts)
>  {
>       struct xfs_btree_cur            *cur = NULL;
> @@ -5607,10 +5636,11 @@ xfs_bmap_shift_extents(
>       struct xfs_ifork                *ifp;
>       xfs_extnum_t                    nexts = 0;
>       xfs_extnum_t                    current_ext;
> +     xfs_extnum_t                    total_extents;
> +     xfs_extnum_t                    stop_extent;
>       int                             error = 0;
>       int                             whichfork = XFS_DATA_FORK;
>       int                             logflags = 0;
> -     int                             total_extents;
>  
>       if (unlikely(XFS_TEST_ERROR(
>           (XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_EXTENTS &&
> @@ -5626,6 +5656,7 @@ xfs_bmap_shift_extents(
>  
>       ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
>       ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
> +     ASSERT(SHIFT == SHIFT_LEFT || SHIFT == SHIFT_RIGHT);
>  
>       ifp = XFS_IFORK_PTR(ip, whichfork);
>       if (!(ifp->if_flags & XFS_IFEXTENTS)) {
> @@ -5643,43 +5674,85 @@ xfs_bmap_shift_extents(
>       }
>  
>       /*
> +      * There may be delalloc extents in the data fork before the range we
> +      * are collapsing out, so we cannot use the count of real extents here.
> +      * Instead we have to calculate it from the incore fork.
> +      */
> +     total_extents = ifp->if_bytes / sizeof(xfs_bmbt_rec_t);
> +     if (total_extents == 0) {
> +             *done = 1;
> +             goto del_cursor;
> +     }
> +
> +     /*
> +      * In case of first right shift, we need to initialize next_fsb
> +      */
> +     if (*next_fsb == NULLFSBLOCK) {
> +             ASSERT(SHIFT == SHIFT_RIGHT);
> +             gotp = xfs_iext_get_ext(ifp, total_extents - 1);
> +             xfs_bmbt_get_all(gotp, &got);
> +             *next_fsb = got.br_startoff;
> +             if (stop_fsb > *next_fsb) {
> +                     *done = 1;
> +                     goto del_cursor;
> +             }
> +     }
> +
> +     /* Lookup the extent index at which we have to stop */
> +     if (SHIFT == SHIFT_RIGHT) {
> +             gotp = xfs_iext_bno_to_ext(ifp, stop_fsb, &stop_extent);
> +             /* Make stop_extent exclusive of shift range */
> +             stop_extent--;
> +     } else
> +             stop_extent = total_extents;
> +
> +     /*
>        * Look up the extent index for the fsb where we start shifting. We can
>        * henceforth iterate with current_ext as extent list changes are locked
>        * out via ilock.
>        *
>        * gotp can be null in 2 cases: 1) if there are no extents or 2)
> -      * start_fsb lies in a hole beyond which there are no extents. Either
> +      * *next_fsb lies in a hole beyond which there are no extents. Either
>        * way, we are done.
>        */
> -     gotp = xfs_iext_bno_to_ext(ifp, start_fsb, &current_ext);
> +     gotp = xfs_iext_bno_to_ext(ifp, *next_fsb, &current_ext);
>       if (!gotp) {
>               *done = 1;
>               goto del_cursor;
>       }
>  
> -     /*
> -      * There may be delalloc extents in the data fork before the range we
> -      * are collapsing out, so we cannot use the count of real extents here.
> -      * Instead we have to calculate it from the incore fork.
> -      */
> -     total_extents = ifp->if_bytes / sizeof(xfs_bmbt_rec_t);
> -     while (nexts++ < num_exts && current_ext < total_extents) {
> +     /* some sanity checking before we finally start shifting extents */
> +     if ((SHIFT == SHIFT_LEFT && current_ext > stop_extent) ||
> +          (SHIFT == SHIFT_RIGHT && current_ext < stop_extent)) {
> +             error = EIO;
> +             goto del_cursor;
> +     }

If stop_extent is consistently exclusive now, we probably need to use >=
and <= here (e.g., 'stop_extent' should never be shifted).

> +
> +     while (nexts++ < num_exts) {
>               error = xfs_bmse_shift_one(ip, whichfork, offset_shift_fsb,
> -                                     &current_ext, gotp, cur, &logflags);
> +                                        &current_ext, gotp, cur, &logflags,
> +                                        SHIFT);
>               if (error)
>                       goto del_cursor;
> +             /*
> +              * In case there was an extent merge after shifting extent,
> +              * extent numbers would change.
> +              * Update total extent count and grab the next record.
> +              */
> +             if (SHIFT == SHIFT_LEFT) {
> +                     total_extents = ifp->if_bytes / sizeof(xfs_bmbt_rec_t);
> +                     stop_extent = total_extents;
> +             }
>  
> -             /* update total extent count and grab the next record */
> -             total_extents = ifp->if_bytes / sizeof(xfs_bmbt_rec_t);
> -             if (current_ext >= total_extents)
> +             if (current_ext == stop_extent) {
> +                     *done = 1;
> +                     *next_fsb = NULLFSBLOCK;
>                       break;
> +             }
>               gotp = xfs_iext_get_ext(ifp, current_ext);
>       }
>  
> -     /* Check if we are done */
> -     if (current_ext == total_extents) {
> -             *done = 1;
> -     } else if (next_fsb) {
> +     if (!*done) {
>               xfs_bmbt_get_all(gotp, &got);
>               *next_fsb = got.br_startoff;
>       }
> @@ -5694,3 +5767,190 @@ del_cursor:
>  
>       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 split. @split_fsb is a block where the extents is split.
> + * 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_fsblock_t           *firstfsb,
> +     struct xfs_bmap_free    *free_list)
> +{
> +     int                             whichfork = XFS_DATA_FORK;
> +     struct xfs_btree_cur            *cur = NULL;
> +     struct xfs_bmbt_rec_host        *gotp;
> +     struct xfs_bmbt_irec            got;
> +     struct xfs_bmbt_irec            new; /* split extent */
> +     struct xfs_mount                *mp = ip->i_mount;
> +     struct xfs_ifork                *ifp;
> +     xfs_fsblock_t                   gotblkcnt; /* new block count for got */
> +     xfs_extnum_t                    current_ext;
> +     int                             error = 0;
> +     int                             logflags = 0;
> +     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 -EFSCORRUPTED;
> +     }
> +
> +     if (XFS_FORCED_SHUTDOWN(mp))
> +             return -EIO;
> +
> +     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;
> +
> +     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;
> +     }
> +
> +     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;
> +
> +     logflags = XFS_ILOG_CORE;
> +     if (cur) {
> +             error = xfs_bmbt_update(cur, got.br_startoff,
> +                             got.br_startblock,
> +                             got.br_blockcount,
> +                             got.br_state);
> +             if (error)
> +                     goto del_cursor;
> +     } else
> +             logflags |= XFS_ILOG_DEXT;
> +
> +     /* 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);

        if (logflags)
                xfs_trans_log_inode(tp, ip, logflags);

Otherwise, the rest looks pretty good. I'll try to do some testing with
it soon.

Brian

> +     return error;
> +}
> +
> +int
> +xfs_bmap_split_extent(
> +     struct xfs_inode        *ip,
> +     xfs_fileoff_t           split_fsb)
> +{
> +     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) {
> +             xfs_trans_cancel(tp, 0);
> +             return error;
> +     }
> +
> +     xfs_ilock(ip, XFS_ILOCK_EXCL);
> +     xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
> +
> +     xfs_bmap_init(&free_list, &firstfsb);
> +
> +     error = xfs_bmap_split_extent_at(tp, ip, split_fsb,
> +                     &firstfsb, &free_list);
> +     if (error)
> +             goto out;
> +
> +     error = xfs_bmap_finish(&tp, &free_list, &committed);
> +     if (error)
> +             goto out;
> +
> +     return xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
> +
> +
> +out:
> +     xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
> +     return error;
> +}
> diff --git a/fs/xfs/libxfs/xfs_bmap.h b/fs/xfs/libxfs/xfs_bmap.h
> index 44db6db..d4678dd 100644
> --- a/fs/xfs/libxfs/xfs_bmap.h
> +++ b/fs/xfs/libxfs/xfs_bmap.h
> @@ -135,6 +135,11 @@ static inline void xfs_bmap_init(xfs_bmap_free_t *flp, 
> xfs_fsblock_t *fbp)
>   */
>  #define XFS_BMAP_MAX_SHIFT_EXTENTS   1
>  
> +enum SHIFT_DIRECTION {
> +     SHIFT_LEFT = 0,
> +     SHIFT_RIGHT,
> +};
> +
>  #ifdef DEBUG
>  void xfs_bmap_trace_exlist(struct xfs_inode *ip, xfs_extnum_t cnt,
>               int whichfork, unsigned long caller_ip);
> @@ -178,8 +183,10 @@ 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,
> -             xfs_fileoff_t start_fsb, xfs_fileoff_t offset_shift_fsb,
> -             int *done, xfs_fileoff_t *next_fsb, xfs_fsblock_t *firstblock,
> -             struct xfs_bmap_free *flist, int num_exts);
> +             xfs_fileoff_t *next_fsb, xfs_fileoff_t offset_shift_fsb,
> +             int *done, xfs_fileoff_t stop_fsb, xfs_fsblock_t *firstblock,
> +             struct xfs_bmap_free *flist, enum SHIFT_DIRECTION SHIFT,
> +             int num_exts);
> +int  xfs_bmap_split_extent(struct xfs_inode *ip, xfs_fileoff_t split_offset);
>  
>  #endif       /* __XFS_BMAP_H__ */
> diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
> index 22a5dcb..841744c 100644
> --- a/fs/xfs/xfs_bmap_util.c
> +++ b/fs/xfs/xfs_bmap_util.c
> @@ -1376,22 +1376,19 @@ out:
>  }
>  
>  /*
> - * xfs_collapse_file_space()
> - *   This routine frees disk space and shift extent for the given file.
> - *   The first thing we do is to free data blocks in the specified range
> - *   by calling xfs_free_file_space(). It would also sync dirty data
> - *   and invalidate page cache over the region on which collapse range
> - *   is working. And Shift extent records to the left to cover a hole.
> - * RETURNS:
> - *   0 on success
> - *   errno on error
> - *
> + * @next_fsb will keep track of the extent currently undergoing shift.
> + * @stop_fsb will keep track of the extent at which we have to stop.
> + * If we are shifting left, we will start with block (offset + len) and
> + * shift each extent till last extent.
> + * If we are shifting right, we will start with last extent inside file space
> + * and continue until we reach the block corresponding to offset.
>   */
>  int
> -xfs_collapse_file_space(
> -     struct xfs_inode        *ip,
> -     xfs_off_t               offset,
> -     xfs_off_t               len)
> +xfs_shift_file_space(
> +     struct xfs_inode        *ip,
> +     xfs_off_t               offset,
> +     xfs_off_t               len,
> +     enum SHIFT_DIRECTION    SHIFT)
>  {
>       int                     done = 0;
>       struct xfs_mount        *mp = ip->i_mount;
> @@ -1400,21 +1397,26 @@ xfs_collapse_file_space(
>       struct xfs_bmap_free    free_list;
>       xfs_fsblock_t           first_block;
>       int                     committed;
> -     xfs_fileoff_t           start_fsb;
> +     xfs_fileoff_t           stop_fsb;
>       xfs_fileoff_t           next_fsb;
>       xfs_fileoff_t           shift_fsb;
>  
> -     ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
> +     ASSERT(SHIFT == SHIFT_LEFT || SHIFT == SHIFT_RIGHT);
>  
> -     trace_xfs_collapse_file_space(ip);
> +     if (SHIFT == SHIFT_LEFT) {
> +             next_fsb = XFS_B_TO_FSB(mp, offset + len);
> +             stop_fsb = XFS_B_TO_FSB(mp, VFS_I(ip)->i_size);
> +     } else {
> +             /*
> +              * If right shift, delegate the work of initialization of
> +              * next_fsb to xfs_bmap_shift_extent as it has ilock held.
> +              */
> +             next_fsb = NULLFSBLOCK;
> +             stop_fsb = XFS_B_TO_FSB(mp, offset);
> +     }
>  
> -     next_fsb = XFS_B_TO_FSB(mp, offset + len);
>       shift_fsb = XFS_B_TO_FSB(mp, len);
>  
> -     error = xfs_free_file_space(ip, offset, len);
> -     if (error)
> -             return error;
> -
>       /*
>        * Trim eofblocks to avoid shifting uninitialized post-eof preallocation
>        * into the accessible region of the file.
> @@ -1427,20 +1429,23 @@ xfs_collapse_file_space(
>  
>       /*
>        * Writeback and invalidate cache for the remainder of the file as we're
> -      * about to shift down every extent from the collapse range to EOF. The
> -      * free of the collapse range above might have already done some of
> -      * this, but we shouldn't rely on it to do anything outside of the range
> -      * that was freed.
> +      * about to shift down every extent from offset to EOF.
>        */
>       error = filemap_write_and_wait_range(VFS_I(ip)->i_mapping,
> -                                          offset + len, -1);
> +                                          offset, -1);
>       if (error)
>               return error;
>       error = invalidate_inode_pages2_range(VFS_I(ip)->i_mapping,
> -                                     (offset + len) >> PAGE_CACHE_SHIFT, -1);
> +                                     offset >> PAGE_CACHE_SHIFT, -1);
>       if (error)
>               return error;
>  
> +     if (SHIFT == SHIFT_RIGHT) {
> +             error = xfs_bmap_split_extent(ip, stop_fsb);
> +             if (error)
> +                     return error;
> +     }
> +
>       while (!error && !done) {
>               tp = xfs_trans_alloc(mp, XFS_TRANS_DIOSTRAT);
>               /*
> @@ -1464,7 +1469,7 @@ xfs_collapse_file_space(
>               if (error)
>                       goto out;
>  
> -             xfs_trans_ijoin(tp, ip, 0);
> +             xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
>  
>               xfs_bmap_init(&free_list, &first_block);
>  
> @@ -1472,10 +1477,9 @@ xfs_collapse_file_space(
>                * We are using the write transaction in which max 2 bmbt
>                * updates are allowed
>                */
> -             start_fsb = next_fsb;
> -             error = xfs_bmap_shift_extents(tp, ip, start_fsb, shift_fsb,
> -                             &done, &next_fsb, &first_block, &free_list,
> -                             XFS_BMAP_MAX_SHIFT_EXTENTS);
> +             error = xfs_bmap_shift_extents(tp, ip, &next_fsb, shift_fsb,
> +                             &done, stop_fsb, &first_block, &free_list,
> +                             SHIFT, XFS_BMAP_MAX_SHIFT_EXTENTS);
>               if (error)
>                       goto out;
>  
> @@ -1484,18 +1488,70 @@ xfs_collapse_file_space(
>                       goto out;
>  
>               error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
> -             xfs_iunlock(ip, XFS_ILOCK_EXCL);
>       }
>  
>       return error;
>  
>  out:
>       xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);
> -     xfs_iunlock(ip, XFS_ILOCK_EXCL);
>       return error;
>  }
>  
>  /*
> + * xfs_collapse_file_space()
> + *   This routine frees disk space and shift extent for the given file.
> + *   The first thing we do is to free data blocks in the specified range
> + *   by calling xfs_free_file_space(). It would also sync dirty data
> + *   and invalidate page cache over the region on which collapse range
> + *   is working. And Shift extent records to the left to cover a hole.
> + * RETURNS:
> + *   0 on success
> + *   errno on error
> + *
> + */
> +int
> +xfs_collapse_file_space(
> +     struct xfs_inode        *ip,
> +     xfs_off_t               offset,
> +     xfs_off_t               len)
> +{
> +     int error;
> +
> +     ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
> +     trace_xfs_collapse_file_space(ip);
> +
> +     error = xfs_free_file_space(ip, offset, len);
> +     if (error)
> +             return error;
> +
> +     return xfs_shift_file_space(ip, offset, len, SHIFT_LEFT);
> +}
> +
> +/*
> + * xfs_insert_file_space()
> + *   This routine create hole space by shifting extents 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.
> + * RETURNS:
> + *   0 on success
> + *   errno on error
> + */
> +int
> +xfs_insert_file_space(
> +     struct xfs_inode        *ip,
> +     loff_t                  offset,
> +     loff_t                  len)
> +{
> +     ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
> +     trace_xfs_insert_file_space(ip);
> +
> +     return xfs_shift_file_space(ip, offset, len, SHIFT_RIGHT);
> +}
> +
> +/*
>   * 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 2fdb72d..6cb116c 100644
> --- a/fs/xfs/xfs_bmap_util.h
> +++ b/fs/xfs/xfs_bmap_util.h
> @@ -98,6 +98,8 @@ 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 13e974e..e68c063 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -787,11 +787,13 @@ 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);
> @@ -821,6 +823,28 @@ 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)) {
> @@ -852,7 +876,8 @@ xfs_file_fallocate(
>       if (ip->i_d.di_mode & S_IXGRP)
>               ip->i_d.di_mode &= ~S_ISGID;
>  
> -     if (!(mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_COLLAPSE_RANGE)))
> +     if (!(mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_COLLAPSE_RANGE |
> +                   FALLOC_FL_INSERT_RANGE)))
>               ip->i_d.di_flags |= XFS_DIFLAG_PREALLOC;
>  
>       xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
> @@ -871,8 +896,20 @@ 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 to create a hole inside the file. 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 51372e3..7e45fa1 100644
> --- a/fs/xfs/xfs_trace.h
> +++ b/fs/xfs/xfs_trace.h
> @@ -664,6 +664,7 @@ 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);
> -- 
> 1.8.5.5
> 

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