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ext4: cleanup bh release code in ext4_ind_remove_space()
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Currently, we are releasing the indirect buffer where we are done with
it in ext4_ind_remove_space(), so we can see the brelse() and
BUFFER_TRACE() everywhere.  It seems fragile and hard to read, and we
may probably forget to release the buffer some day.  This patch cleans
up the code by putting of the code which releases the buffers to the
end of the function.

Signed-off-by: zhangyi (F) <[email protected]>
Signed-off-by: Theodore Ts'o <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
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@zhangyi089 @tytso
zhangyi089 authored and tytso committed Mar 23, 2019
1 parent 674a2b2 commit 5e86bdd
Showing 1 changed file with 22 additions and 25 deletions.
47 changes: 22 additions & 25 deletions fs/ext4/indirect.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1222,6 +1222,7 @@ int ext4_ind_remove_space(handle_t *handle, struct inode *inode,
ext4_lblk_t offsets[4], offsets2[4];
Indirect chain[4], chain2[4];
Indirect *partial, *partial2;
Indirect *p = NULL, *p2 = NULL;
ext4_lblk_t max_block;
__le32 nr = 0, nr2 = 0;
int n = 0, n2 = 0;
Expand Down Expand Up @@ -1263,7 +1264,7 @@ int ext4_ind_remove_space(handle_t *handle, struct inode *inode,
}


partial = ext4_find_shared(inode, n, offsets, chain, &nr);
partial = p = ext4_find_shared(inode, n, offsets, chain, &nr);
if (nr) {
if (partial == chain) {
/* Shared branch grows from the inode */
Expand All @@ -1288,13 +1289,11 @@ int ext4_ind_remove_space(handle_t *handle, struct inode *inode,
partial->p + 1,
(__le32 *)partial->bh->b_data+addr_per_block,
(chain+n-1) - partial);
BUFFER_TRACE(partial->bh, "call brelse");
brelse(partial->bh);
partial--;
}

end_range:
partial2 = ext4_find_shared(inode, n2, offsets2, chain2, &nr2);
partial2 = p2 = ext4_find_shared(inode, n2, offsets2, chain2, &nr2);
if (nr2) {
if (partial2 == chain2) {
/*
Expand Down Expand Up @@ -1324,16 +1323,14 @@ int ext4_ind_remove_space(handle_t *handle, struct inode *inode,
(__le32 *)partial2->bh->b_data,
partial2->p,
(chain2+n2-1) - partial2);
BUFFER_TRACE(partial2->bh, "call brelse");
brelse(partial2->bh);
partial2--;
}
goto do_indirects;
}

/* Punch happened within the same level (n == n2) */
partial = ext4_find_shared(inode, n, offsets, chain, &nr);
partial2 = ext4_find_shared(inode, n2, offsets2, chain2, &nr2);
partial = p = ext4_find_shared(inode, n, offsets, chain, &nr);
partial2 = p2 = ext4_find_shared(inode, n2, offsets2, chain2, &nr2);

/* Free top, but only if partial2 isn't its subtree. */
if (nr) {
Expand Down Expand Up @@ -1390,15 +1387,7 @@ int ext4_ind_remove_space(handle_t *handle, struct inode *inode,
partial->p + 1,
partial2->p,
(chain+n-1) - partial);
while (partial > chain) {
BUFFER_TRACE(partial->bh, "call brelse");
brelse(partial->bh);
}
while (partial2 > chain2) {
BUFFER_TRACE(partial2->bh, "call brelse");
brelse(partial2->bh);
}
return 0;
goto cleanup;
}

/*
Expand All @@ -1413,28 +1402,36 @@ int ext4_ind_remove_space(handle_t *handle, struct inode *inode,
partial->p + 1,
(__le32 *)partial->bh->b_data+addr_per_block,
(chain+n-1) - partial);
BUFFER_TRACE(partial->bh, "call brelse");
brelse(partial->bh);
partial--;
}
if (partial2 > chain2 && depth2 <= depth) {
ext4_free_branches(handle, inode, partial2->bh,
(__le32 *)partial2->bh->b_data,
partial2->p,
(chain2+n2-1) - partial2);
BUFFER_TRACE(partial2->bh, "call brelse");
brelse(partial2->bh);
partial2--;
}
}

cleanup:
while (p && p > chain) {
BUFFER_TRACE(p->bh, "call brelse");
brelse(p->bh);
p--;
}
while (p2 && p2 > chain2) {
BUFFER_TRACE(p2->bh, "call brelse");
brelse(p2->bh);
p2--;
}
return 0;

do_indirects:
/* Kill the remaining (whole) subtrees */
switch (offsets[0]) {
default:
if (++n >= n2)
return 0;
break;
nr = i_data[EXT4_IND_BLOCK];
if (nr) {
ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1);
Expand All @@ -1443,7 +1440,7 @@ int ext4_ind_remove_space(handle_t *handle, struct inode *inode,
/* fall through */
case EXT4_IND_BLOCK:
if (++n >= n2)
return 0;
break;
nr = i_data[EXT4_DIND_BLOCK];
if (nr) {
ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2);
Expand All @@ -1452,7 +1449,7 @@ int ext4_ind_remove_space(handle_t *handle, struct inode *inode,
/* fall through */
case EXT4_DIND_BLOCK:
if (++n >= n2)
return 0;
break;
nr = i_data[EXT4_TIND_BLOCK];
if (nr) {
ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3);
Expand All @@ -1462,5 +1459,5 @@ int ext4_ind_remove_space(handle_t *handle, struct inode *inode,
case EXT4_TIND_BLOCK:
;
}
return 0;
goto cleanup;
}

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