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xfs: don't rely on extent indices in xfs_bmap_insert_extents 

Rewrite xfs_bmap_insert_extents so that we don't rely on extent indices
except for iterating over them.  Not being able to iterate to the previous
extent or finding the extent that stop_fsb is in are sufficient exit
conditions, and we don't need to do any extent count games given that:

  a) we already flushed all delalloc extents past our start offset
     before doing the operation
  b) xfs_iext_count() includes delalloc extents anyway

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
This commit is contained in:
Christoph Hellwig 2017-10-19 11:08:52 -07:00 committed by Darrick J. Wong
parent 40591bdbcc
commit 5936dc543c
1 changed files with 9 additions and 38 deletions
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47
fs/xfs/libxfs/xfs_bmap.c
View File

@ -5737,10 +5737,8 @@ xfs_bmap_insert_extents(
struct xfs_mount *mp = ip->i_mount;
struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, whichfork);
struct xfs_btree_cur *cur = NULL;
struct xfs_bmbt_irec got, next, s;
struct xfs_bmbt_irec got, next;
xfs_extnum_t current_ext;
xfs_extnum_t total_extents;
xfs_extnum_t stop_extent;
xfs_fileoff_t new_startoff;
int error = 0;
int logflags = 0;
@ -5771,37 +5769,14 @@ xfs_bmap_insert_extents(
cur->bc_private.b.flags = 0;
}
/*
* 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 = xfs_iext_count(ifp);
if (total_extents == 0) {
*done = true;
goto del_cursor;
}
/*
* In case of first right shift, we need to initialize next_fsb
*/
if (*next_fsb == NULLFSBLOCK) {
current_ext = total_extents - 1;
xfs_iext_get_extent(ifp, current_ext, &got);
if (stop_fsb > got.br_startoff) {
current_ext = xfs_iext_count(ifp) - 1;
if (!xfs_iext_get_extent(ifp, current_ext, &got) ||
stop_fsb > got.br_startoff) {
*done = true;
goto del_cursor;
}
*next_fsb = got.br_startoff;
} else {
/*
* 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.
*
* If next_fsb lies in a hole beyond which there are no extents we are
* done.
*/
if (!xfs_iext_lookup_extent(ip, ifp, *next_fsb, &current_ext,
&got)) {
*done = true;
@ -5810,18 +5785,13 @@ xfs_bmap_insert_extents(
}
XFS_WANT_CORRUPTED_RETURN(mp, !isnullstartblock(got.br_startblock));
/* Lookup the extent index at which we have to stop */
xfs_iext_lookup_extent(ip, ifp, stop_fsb, &stop_extent, &s);
/* Make stop_extent exclusive of shift range */
stop_extent--;
if (current_ext <= stop_extent) {
if (stop_fsb >= got.br_startoff + got.br_blockcount) {
error = -EIO;
goto del_cursor;
}
new_startoff = got.br_startoff + offset_shift_fsb;
if (current_ext < total_extents - 1) {
xfs_iext_get_extent(ifp, current_ext + 1, &next);
if (xfs_iext_get_extent(ifp, current_ext + 1, &next)) {
if (new_startoff + got.br_blockcount > next.br_startoff) {
error = -EINVAL;
goto del_cursor;
@ -5841,11 +5811,12 @@ xfs_bmap_insert_extents(
cur, &logflags, dfops, new_startoff);
if (error)
goto del_cursor;
if (--current_ext == stop_extent) {
if (!xfs_iext_get_extent(ifp, --current_ext, &got) ||
stop_fsb >= got.br_startoff + got.br_blockcount) {
*done = true;
goto del_cursor;
}
xfs_iext_get_extent(ifp, current_ext, &got);
*next_fsb = got.br_startoff;
del_cursor: