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Date: Mon, 18 Mar 2019 12:10:56 +0100
From: Jan Kara <jack@...e.cz>
To: "zhangyi (F)" <yi.zhang@...wei.com>
Cc: linux-ext4@...r.kernel.org, tytso@....edu, jack@...e.cz,
adilger.kernel@...ger.ca, miaoxie@...wei.com
Subject: Re: [PATCH v2 2/2] ext4: cleanup bh release code in
ext4_ind_remove_space()
On Fri 15-03-19 15:10:13, zhangyi (F) wrote:
> 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 do some
> cleanup stuff, put all the releasing code together to the end of this
> function.
>
> Signed-off-by: zhangyi (F) <yi.zhang@...wei.com>
OK, now when the cleanup is separate, I actually like it. So feel free to
add:
Reviewed-by: Jan Kara <jack@...e.cz>
Honza
> ---
> fs/ext4/indirect.c | 47 ++++++++++++++++++++++-------------------------
> 1 file changed, 22 insertions(+), 25 deletions(-)
>
> diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c
> index 9e96a0b..e1801b2 100644
> --- a/fs/ext4/indirect.c
> +++ b/fs/ext4/indirect.c
> @@ -1219,6 +1219,7 @@ 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;
> @@ -1260,7 +1261,7 @@ 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 */
> @@ -1285,13 +1286,11 @@ 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) {
> /*
> @@ -1321,16 +1320,14 @@ 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) {
> @@ -1387,15 +1384,7 @@ 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;
> }
>
> /*
> @@ -1410,8 +1399,6 @@ 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) {
> @@ -1419,11 +1406,21 @@ 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--;
> }
> }
> +
> +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:
> @@ -1431,7 +1428,7 @@ int ext4_ind_remove_space(handle_t *handle, struct inode *inode,
> 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);
> @@ -1439,7 +1436,7 @@ int ext4_ind_remove_space(handle_t *handle, struct inode *inode,
> }
> 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);
> @@ -1447,7 +1444,7 @@ int ext4_ind_remove_space(handle_t *handle, struct inode *inode,
> }
> 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);
> @@ -1456,5 +1453,5 @@ int ext4_ind_remove_space(handle_t *handle, struct inode *inode,
> case EXT4_TIND_BLOCK:
> ;
> }
> - return 0;
> + goto cleanup;
> }
> --
> 2.7.4
>
--
Jan Kara <jack@...e.com>
SUSE Labs, CR
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