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From: fdmanana@kernel.org
To: linux-btrfs@vger.kernel.org
Subject: [PATCH 03/11] btrfs: tag as unlikely branches that call extent_io_tree_panic()
Date: Mon, 16 Mar 2026 16:14:06 +0000	[thread overview]
Message-ID: <5dcbfac4fdd15ca6693668ca01c93b5d1121705f.1773676775.git.fdmanana@suse.com> (raw)
In-Reply-To: <cover.1773676775.git.fdmanana@suse.com>

From: Filipe Manana <fdmanana@suse.com>

It's unexpected to ever call extent_io_tree_panic() so surround with
'unlikely' every if statement condition that leads to it, making it
explicit to a reader and to hint the compiler to potentially generate
better code.

On x86_64, using gcc 14.2.0-19 from Debian, this resulted in a slightly
decrease of the btrfs module's text size.

Before:

  $ size fs/btrfs/btrfs.ko
     text	   data	    bss	    dec	    hex	filename
  1999832	 174320	  15592	2189744	 2169b0	fs/btrfs/btrfs.ko

After:

  $ size fs/btrfs/btrfs.ko
     text	   data	    bss	    dec	    hex	filename
  1999768	 174320	  15592	2189680	 216970	fs/btrfs/btrfs.ko

Signed-off-by: Filipe Manana <fdmanana@suse.com>
---
 fs/btrfs/extent-io-tree.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/fs/btrfs/extent-io-tree.c b/fs/btrfs/extent-io-tree.c
index 68e48b493950..93dca9199249 100644
--- a/fs/btrfs/extent-io-tree.c
+++ b/fs/btrfs/extent-io-tree.c
@@ -696,7 +696,7 @@ int btrfs_clear_extent_bit_changeset(struct extent_io_tree *tree, u64 start, u64
 			goto search_again;
 		ret = split_state(tree, state, prealloc, start);
 		prealloc = NULL;
-		if (ret) {
+		if (unlikely(ret)) {
 			extent_io_tree_panic(tree, state, "split", ret);
 			goto out;
 		}
@@ -762,7 +762,7 @@ int btrfs_clear_extent_bit_changeset(struct extent_io_tree *tree, u64 start, u64
 		if (!prealloc)
 			goto search_again;
 		ret = split_state(tree, state, prealloc, end + 1);
-		if (ret) {
+		if (unlikely(ret)) {
 			extent_io_tree_panic(tree, state, "split", ret);
 			prealloc = NULL;
 			goto out;
@@ -1203,7 +1203,7 @@ static int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 		if (!prealloc)
 			goto search_again;
 		ret = split_state(tree, state, prealloc, start);
-		if (ret)
+		if (unlikely(ret))
 			extent_io_tree_panic(tree, state, "split", ret);
 
 		prealloc = NULL;
@@ -1293,7 +1293,7 @@ static int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 		if (!prealloc)
 			goto search_again;
 		ret = split_state(tree, state, prealloc, end + 1);
-		if (ret) {
+		if (unlikely(ret)) {
 			extent_io_tree_panic(tree, state, "split", ret);
 			prealloc = NULL;
 			goto out;
@@ -1448,7 +1448,7 @@ int btrfs_convert_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 		}
 		ret = split_state(tree, state, prealloc, start);
 		prealloc = NULL;
-		if (ret) {
+		if (unlikely(ret)) {
 			extent_io_tree_panic(tree, state, "split", ret);
 			goto out;
 		}
@@ -1532,7 +1532,7 @@ int btrfs_convert_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 		}
 
 		ret = split_state(tree, state, prealloc, end + 1);
-		if (ret) {
+		if (unlikely(ret)) {
 			extent_io_tree_panic(tree, state, "split", ret);
 			prealloc = NULL;
 			goto out;
-- 
2.47.2


  parent reply	other threads:[~2026-03-16 16:14 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-03-16 16:14 [PATCH 00/11] btrfs: some optimizations and cleanups for io trees fdmanana
2026-03-16 16:14 ` [PATCH 01/11] btrfs: optimize clearing all bits from the last extent record in an io tree fdmanana
2026-03-16 16:14 ` [PATCH 02/11] btrfs: turn extent_io_tree_panic() into a macro for better error reporting fdmanana
2026-03-16 16:14 ` fdmanana [this message]
2026-03-16 16:14 ` [PATCH 04/11] btrfs: make add_extent_changeset() only return errors or success fdmanana
2026-03-16 16:14 ` [PATCH 05/11] btrfs: use extent_io_tree_panic() instead of BUG_ON() fdmanana
2026-03-16 16:14 ` [PATCH 06/11] btrfs: change last argument of add_extent_changeset() to boolean fdmanana
2026-03-16 16:14 ` [PATCH 07/11] btrfs: remove wake parameter from clear_state_bit() fdmanana
2026-03-16 16:14 ` [PATCH 08/11] btrfs: avoid unnecessary wake ups on io trees when there are no waiters fdmanana
2026-03-16 16:14 ` [PATCH 09/11] btrfs: free cached state outside critical section in wait_extent_bit() fdmanana
2026-03-16 16:14 ` [PATCH 10/11] btrfs: panic instead of warn when splitting extent state not in the tree fdmanana
2026-03-16 16:14 ` [PATCH 11/11] btrfs: optimize clearing all bits from first extent record in an io tree fdmanana
2026-03-18 11:02 ` [PATCH 00/11] btrfs: some optimizations and cleanups for io trees David Sterba

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