[f2fs-dev] [PATCH] f2fs: don't reopen the main block device in f2fs_scan_devices

[f2fs-dev] [PATCH] f2fs: don't reopen the main block device in f2fs_scan_devices

[Christoph Hellwig]

f2fs_scan_devices reopens the main device since the very beginning, which
has always been useless, and also means that we don't pass the right
holder for the reopen, which now leads to a warning as the core super.c
holder ops aren't passed in for the reopen.

Fixes: 3c62be17d4f5 ("f2fs: support multiple devices")
Fixes: 0718afd47f70 ("block: introduce holder ops")
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/f2fs/super.c | 20 ++++++++------------
 1 file changed, 8 insertions(+), 12 deletions(-)

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index ca31163da00a55..8d11d4a5ec331d 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1560,7 +1560,8 @@ static void destroy_device_list(struct f2fs_sb_info *sbi)
 {
 	int i;
 
-	for (i = 0; i < sbi->s_ndevs; i++) {
+	kvfree(FDEV(0).blkz_seq);
+	for (i = 1; i < sbi->s_ndevs; i++) {
 		blkdev_put(FDEV(i).bdev, sbi->sb->s_type);
 #ifdef CONFIG_BLK_DEV_ZONED
 		kvfree(FDEV(i).blkz_seq);
@@ -4190,16 +4191,12 @@ static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
 	sbi->aligned_blksize = true;
 
 	for (i = 0; i < max_devices; i++) {
-
-		if (i > 0 && !RDEV(i).path[0])
+		if (i == 0)
+			FDEV(0).bdev = sbi->sb->s_bdev;
+		else if (!RDEV(i).path[0])
 			break;
 
-		if (max_devices == 1) {
-			/* Single zoned block device mount */
-			FDEV(0).bdev =
-				blkdev_get_by_dev(sbi->sb->s_bdev->bd_dev, mode,
-						  sbi->sb->s_type, NULL);
-		} else {
+		if (max_devices > 1) {
 			/* Multi-device mount */
 			memcpy(FDEV(i).path, RDEV(i).path, MAX_PATH_LEN);
 			FDEV(i).total_segments =
@@ -4215,10 +4212,9 @@ static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
 				FDEV(i).end_blk = FDEV(i).start_blk +
 					(FDEV(i).total_segments <<
 					sbi->log_blocks_per_seg) - 1;
+				FDEV(i).bdev = blkdev_get_by_path(FDEV(i).path,
+					mode, sbi->sb->s_type, NULL);
 			}
-			FDEV(i).bdev = blkdev_get_by_path(FDEV(i).path, mode,
-							  sbi->sb->s_type,
-							  NULL);
 		}
 		if (IS_ERR(FDEV(i).bdev))
 			return PTR_ERR(FDEV(i).bdev);
-- 
2.39.2



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Re: [f2fs-dev] [PATCH] f2fs: don't reopen the main block device in f2fs_scan_devices

[Jaegeuk Kim]

Hit a kernel panic with single device.

[  148.003511] BUG: kernel NULL pointer dereference, address: 0000000000000058
[  148.005630] #PF: supervisor read access in kernel mode
[  148.008179] #PF: error_code(0x0000) - not-present page
[  148.010593] PGD 0 P4D 0
[  148.011867] Oops: 0000 [#1] PREEMPT SMP PTI
[  148.014619] CPU: 4 PID: 1905 Comm: umount Tainted: G           OE      6.5.0-rc1-custom #19
[  148.020358] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
[  148.024967] RIP: 0010:destroy_device_list+0x18/0x90 [f2fs]
[  148.027688] Code: 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 55 48 89 e5 41 55 41 54 49 89 fc 53 48 8b 87 40 0b 00 00 <48> 8b 78 58 e8 cf 3e 28 cf 41 83 bc 24 3c 0b 00 00 01 7e 4a 41 bd
[  148.038517] RSP: 0018:ffffa24e80be3d28 EFLAGS: 00010202
[  148.040978] RAX: 0000000000000000 RBX: ffff8bd5503bc800 RCX: 0000000080080006
[  148.044292] RDX: 0000000080080007 RSI: ffffdcfe844da200 RDI: ffff8bd55368d000
[  148.047688] RBP: ffffa24e80be3d40 R08: ffff8bd553688000 R09: 0000000080080006
[  148.051317] R10: ffff8bd5580d4e80 R11: ffff8bd57bd00000 R12: ffff8bd55368d000
[  148.054981] R13: 0000000000000000 R14: ffff8bd55368db18 R15: 0000000000000000
[  148.058391] FS:  00007fc247124800(0000) GS:ffff8bd57bd00000(0000) knlGS:0000000000000000
[  148.062549] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  148.065641] CR2: 0000000000000058 CR3: 0000000001120004 CR4: 0000000000370ee0
[  148.069178] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  148.072651] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  148.076346] Call Trace:
[  148.077641]  <TASK>
[  148.078839]  ? show_regs+0x6a/0x80
[  148.080475]  ? __die+0x25/0x70
[  148.082045]  ? page_fault_oops+0x160/0x480
[  148.084381]  ? check_preempt_wakeup+0x192/0x2f0
[  148.086840]  ? do_user_addr_fault+0x313/0x680
[  148.088999]  ? exc_page_fault+0x79/0x180
[  148.090899]  ? asm_exc_page_fault+0x27/0x30
[  148.093114]  ? destroy_device_list+0x18/0x90 [f2fs]
[  148.095448]  f2fs_put_super+0x211/0x410 [f2fs]
[  148.097871]  ? fscrypt_destroy_keyring+0x110/0x170
[  148.100313]  generic_shutdown_super+0x84/0x1b0
[  148.102582]  kill_block_super+0x24/0x50
[  148.104697]  kill_f2fs_super+0x83/0x100 [f2fs]
[  148.106974]  deactivate_locked_super+0x35/0xb0
[  148.109978]  deactivate_super+0x44/0x50
[  148.112235]  cleanup_mnt+0x105/0x160
[  148.114407]  __cleanup_mnt+0x12/0x20
[  148.116680]  task_work_run+0x61/0x90
[  148.118961]  exit_to_user_mode_prepare+0x18f/0x1a0
[  148.121812]  syscall_exit_to_user_mode+0x26/0x50
[  148.124595]  do_syscall_64+0x69/0x90
[  148.126616]  ? exc_page_fault+0x8a/0x180
[  148.128742]  entry_SYSCALL_64_after_hwframe+0x6e/0xd8
[  148.131521] RIP: 0033:0x7fc246f24a7b

On 07/07, Christoph Hellwig wrote:
> f2fs_scan_devices reopens the main device since the very beginning, which
> has always been useless, and also means that we don't pass the right
> holder for the reopen, which now leads to a warning as the core super.c
> holder ops aren't passed in for the reopen.
> 
> Fixes: 3c62be17d4f5 ("f2fs: support multiple devices")
> Fixes: 0718afd47f70 ("block: introduce holder ops")
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  fs/f2fs/super.c | 20 ++++++++------------
>  1 file changed, 8 insertions(+), 12 deletions(-)
> 
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index ca31163da00a55..8d11d4a5ec331d 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -1560,7 +1560,8 @@ static void destroy_device_list(struct f2fs_sb_info *sbi)
>  {
>  	int i;
>  
> -	for (i = 0; i < sbi->s_ndevs; i++) {

#ifdef CONFIG_BLK_DEV_ZONED

> +	kvfree(FDEV(0).blkz_seq);

#endif

> +	for (i = 1; i < sbi->s_ndevs; i++) {
>  		blkdev_put(FDEV(i).bdev, sbi->sb->s_type);
>  #ifdef CONFIG_BLK_DEV_ZONED
>  		kvfree(FDEV(i).blkz_seq);
> @@ -4190,16 +4191,12 @@ static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
>  	sbi->aligned_blksize = true;
>  
>  	for (i = 0; i < max_devices; i++) {
> -
> -		if (i > 0 && !RDEV(i).path[0])
> +		if (i == 0)
> +			FDEV(0).bdev = sbi->sb->s_bdev;
> +		else if (!RDEV(i).path[0])
>  			break;
>  
> -		if (max_devices == 1) {
> -			/* Single zoned block device mount */
> -			FDEV(0).bdev =
> -				blkdev_get_by_dev(sbi->sb->s_bdev->bd_dev, mode,
> -						  sbi->sb->s_type, NULL);
> -		} else {
> +		if (max_devices > 1) {
>  			/* Multi-device mount */
>  			memcpy(FDEV(i).path, RDEV(i).path, MAX_PATH_LEN);
>  			FDEV(i).total_segments =
> @@ -4215,10 +4212,9 @@ static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
>  				FDEV(i).end_blk = FDEV(i).start_blk +
>  					(FDEV(i).total_segments <<
>  					sbi->log_blocks_per_seg) - 1;
> +				FDEV(i).bdev = blkdev_get_by_path(FDEV(i).path,
> +					mode, sbi->sb->s_type, NULL);
>  			}
> -			FDEV(i).bdev = blkdev_get_by_path(FDEV(i).path, mode,
> -							  sbi->sb->s_type,
> -							  NULL);
>  		}
>  		if (IS_ERR(FDEV(i).bdev))
>  			return PTR_ERR(FDEV(i).bdev);
> -- 
> 2.39.2


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Re: [f2fs-dev] [PATCH] f2fs: don't reopen the main block device in f2fs_scan_devices

[Damien Le Moal]

On 7/11/23 06:22, Jaegeuk Kim wrote:
> Hit a kernel panic with single device.
> 
> [  148.003511] BUG: kernel NULL pointer dereference, address: 0000000000000058
> [  148.005630] #PF: supervisor read access in kernel mode
> [  148.008179] #PF: error_code(0x0000) - not-present page
> [  148.010593] PGD 0 P4D 0
> [  148.011867] Oops: 0000 [#1] PREEMPT SMP PTI
> [  148.014619] CPU: 4 PID: 1905 Comm: umount Tainted: G           OE      6.5.0-rc1-custom #19
> [  148.020358] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> [  148.024967] RIP: 0010:destroy_device_list+0x18/0x90 [f2fs]
> [  148.027688] Code: 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 55 48 89 e5 41 55 41 54 49 89 fc 53 48 8b 87 40 0b 00 00 <48> 8b 78 58 e8 cf 3e 28 cf 41 83 bc 24 3c 0b 00 00 01 7e 4a 41 bd
> [  148.038517] RSP: 0018:ffffa24e80be3d28 EFLAGS: 00010202
> [  148.040978] RAX: 0000000000000000 RBX: ffff8bd5503bc800 RCX: 0000000080080006
> [  148.044292] RDX: 0000000080080007 RSI: ffffdcfe844da200 RDI: ffff8bd55368d000
> [  148.047688] RBP: ffffa24e80be3d40 R08: ffff8bd553688000 R09: 0000000080080006
> [  148.051317] R10: ffff8bd5580d4e80 R11: ffff8bd57bd00000 R12: ffff8bd55368d000
> [  148.054981] R13: 0000000000000000 R14: ffff8bd55368db18 R15: 0000000000000000
> [  148.058391] FS:  00007fc247124800(0000) GS:ffff8bd57bd00000(0000) knlGS:0000000000000000
> [  148.062549] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [  148.065641] CR2: 0000000000000058 CR3: 0000000001120004 CR4: 0000000000370ee0
> [  148.069178] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [  148.072651] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [  148.076346] Call Trace:
> [  148.077641]  <TASK>
> [  148.078839]  ? show_regs+0x6a/0x80
> [  148.080475]  ? __die+0x25/0x70
> [  148.082045]  ? page_fault_oops+0x160/0x480
> [  148.084381]  ? check_preempt_wakeup+0x192/0x2f0
> [  148.086840]  ? do_user_addr_fault+0x313/0x680
> [  148.088999]  ? exc_page_fault+0x79/0x180
> [  148.090899]  ? asm_exc_page_fault+0x27/0x30
> [  148.093114]  ? destroy_device_list+0x18/0x90 [f2fs]
> [  148.095448]  f2fs_put_super+0x211/0x410 [f2fs]
> [  148.097871]  ? fscrypt_destroy_keyring+0x110/0x170
> [  148.100313]  generic_shutdown_super+0x84/0x1b0
> [  148.102582]  kill_block_super+0x24/0x50
> [  148.104697]  kill_f2fs_super+0x83/0x100 [f2fs]
> [  148.106974]  deactivate_locked_super+0x35/0xb0
> [  148.109978]  deactivate_super+0x44/0x50
> [  148.112235]  cleanup_mnt+0x105/0x160
> [  148.114407]  __cleanup_mnt+0x12/0x20
> [  148.116680]  task_work_run+0x61/0x90
> [  148.118961]  exit_to_user_mode_prepare+0x18f/0x1a0
> [  148.121812]  syscall_exit_to_user_mode+0x26/0x50
> [  148.124595]  do_syscall_64+0x69/0x90
> [  148.126616]  ? exc_page_fault+0x8a/0x180
> [  148.128742]  entry_SYSCALL_64_after_hwframe+0x6e/0xd8
> [  148.131521] RIP: 0033:0x7fc246f24a7b
> 
> On 07/07, Christoph Hellwig wrote:
>> f2fs_scan_devices reopens the main device since the very beginning, which
>> has always been useless, and also means that we don't pass the right
>> holder for the reopen, which now leads to a warning as the core super.c
>> holder ops aren't passed in for the reopen.
>>
>> Fixes: 3c62be17d4f5 ("f2fs: support multiple devices")
>> Fixes: 0718afd47f70 ("block: introduce holder ops")
>> Signed-off-by: Christoph Hellwig <hch@lst.de>
>> ---
>>  fs/f2fs/super.c | 20 ++++++++------------
>>  1 file changed, 8 insertions(+), 12 deletions(-)
>>
>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
>> index ca31163da00a55..8d11d4a5ec331d 100644
>> --- a/fs/f2fs/super.c
>> +++ b/fs/f2fs/super.c
>> @@ -1560,7 +1560,8 @@ static void destroy_device_list(struct f2fs_sb_info *sbi)
>>  {
>>  	int i;
>>  
>> -	for (i = 0; i < sbi->s_ndevs; i++) {
> 
> #ifdef CONFIG_BLK_DEV_ZONED
> 
>> +	kvfree(FDEV(0).blkz_seq);
> 
> #endif

This should not be needed since for the !CONFIG_BLK_DEV_ZONED case,
FDEV(0).blkz_seq should always be NULL. However, what I think may be missing is
"FDEV(0).blkz_seq = NULL;" after the kvfree() call. No ?

> 
>> +	for (i = 1; i < sbi->s_ndevs; i++) {
>>  		blkdev_put(FDEV(i).bdev, sbi->sb->s_type);
>>  #ifdef CONFIG_BLK_DEV_ZONED
>>  		kvfree(FDEV(i).blkz_seq);
>> @@ -4190,16 +4191,12 @@ static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
>>  	sbi->aligned_blksize = true;
>>  
>>  	for (i = 0; i < max_devices; i++) {
>> -
>> -		if (i > 0 && !RDEV(i).path[0])
>> +		if (i == 0)
>> +			FDEV(0).bdev = sbi->sb->s_bdev;
>> +		else if (!RDEV(i).path[0])
>>  			break;
>>  
>> -		if (max_devices == 1) {
>> -			/* Single zoned block device mount */
>> -			FDEV(0).bdev =
>> -				blkdev_get_by_dev(sbi->sb->s_bdev->bd_dev, mode,
>> -						  sbi->sb->s_type, NULL);
>> -		} else {
>> +		if (max_devices > 1) {
>>  			/* Multi-device mount */
>>  			memcpy(FDEV(i).path, RDEV(i).path, MAX_PATH_LEN);
>>  			FDEV(i).total_segments =
>> @@ -4215,10 +4212,9 @@ static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
>>  				FDEV(i).end_blk = FDEV(i).start_blk +
>>  					(FDEV(i).total_segments <<
>>  					sbi->log_blocks_per_seg) - 1;
>> +				FDEV(i).bdev = blkdev_get_by_path(FDEV(i).path,
>> +					mode, sbi->sb->s_type, NULL);
>>  			}
>> -			FDEV(i).bdev = blkdev_get_by_path(FDEV(i).path, mode,
>> -							  sbi->sb->s_type,
>> -							  NULL);
>>  		}
>>  		if (IS_ERR(FDEV(i).bdev))
>>  			return PTR_ERR(FDEV(i).bdev);
>> -- 
>> 2.39.2

-- 
Damien Le Moal
Western Digital Research



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Re: [f2fs-dev] [PATCH] f2fs: don't reopen the main block device in f2fs_scan_devices

[Jaegeuk Kim]

On 07/11, Damien Le Moal wrote:
> On 7/11/23 06:22, Jaegeuk Kim wrote:
> > Hit a kernel panic with single device.
> > 
> > [  148.003511] BUG: kernel NULL pointer dereference, address: 0000000000000058
> > [  148.005630] #PF: supervisor read access in kernel mode
> > [  148.008179] #PF: error_code(0x0000) - not-present page
> > [  148.010593] PGD 0 P4D 0
> > [  148.011867] Oops: 0000 [#1] PREEMPT SMP PTI
> > [  148.014619] CPU: 4 PID: 1905 Comm: umount Tainted: G           OE      6.5.0-rc1-custom #19
> > [  148.020358] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> > [  148.024967] RIP: 0010:destroy_device_list+0x18/0x90 [f2fs]
> > [  148.027688] Code: 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 55 48 89 e5 41 55 41 54 49 89 fc 53 48 8b 87 40 0b 00 00 <48> 8b 78 58 e8 cf 3e 28 cf 41 83 bc 24 3c 0b 00 00 01 7e 4a 41 bd
> > [  148.038517] RSP: 0018:ffffa24e80be3d28 EFLAGS: 00010202
> > [  148.040978] RAX: 0000000000000000 RBX: ffff8bd5503bc800 RCX: 0000000080080006
> > [  148.044292] RDX: 0000000080080007 RSI: ffffdcfe844da200 RDI: ffff8bd55368d000
> > [  148.047688] RBP: ffffa24e80be3d40 R08: ffff8bd553688000 R09: 0000000080080006
> > [  148.051317] R10: ffff8bd5580d4e80 R11: ffff8bd57bd00000 R12: ffff8bd55368d000
> > [  148.054981] R13: 0000000000000000 R14: ffff8bd55368db18 R15: 0000000000000000
> > [  148.058391] FS:  00007fc247124800(0000) GS:ffff8bd57bd00000(0000) knlGS:0000000000000000
> > [  148.062549] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > [  148.065641] CR2: 0000000000000058 CR3: 0000000001120004 CR4: 0000000000370ee0
> > [  148.069178] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > [  148.072651] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > [  148.076346] Call Trace:
> > [  148.077641]  <TASK>
> > [  148.078839]  ? show_regs+0x6a/0x80
> > [  148.080475]  ? __die+0x25/0x70
> > [  148.082045]  ? page_fault_oops+0x160/0x480
> > [  148.084381]  ? check_preempt_wakeup+0x192/0x2f0
> > [  148.086840]  ? do_user_addr_fault+0x313/0x680
> > [  148.088999]  ? exc_page_fault+0x79/0x180
> > [  148.090899]  ? asm_exc_page_fault+0x27/0x30
> > [  148.093114]  ? destroy_device_list+0x18/0x90 [f2fs]
> > [  148.095448]  f2fs_put_super+0x211/0x410 [f2fs]
> > [  148.097871]  ? fscrypt_destroy_keyring+0x110/0x170
> > [  148.100313]  generic_shutdown_super+0x84/0x1b0
> > [  148.102582]  kill_block_super+0x24/0x50
> > [  148.104697]  kill_f2fs_super+0x83/0x100 [f2fs]
> > [  148.106974]  deactivate_locked_super+0x35/0xb0
> > [  148.109978]  deactivate_super+0x44/0x50
> > [  148.112235]  cleanup_mnt+0x105/0x160
> > [  148.114407]  __cleanup_mnt+0x12/0x20
> > [  148.116680]  task_work_run+0x61/0x90
> > [  148.118961]  exit_to_user_mode_prepare+0x18f/0x1a0
> > [  148.121812]  syscall_exit_to_user_mode+0x26/0x50
> > [  148.124595]  do_syscall_64+0x69/0x90
> > [  148.126616]  ? exc_page_fault+0x8a/0x180
> > [  148.128742]  entry_SYSCALL_64_after_hwframe+0x6e/0xd8
> > [  148.131521] RIP: 0033:0x7fc246f24a7b
> > 
> > On 07/07, Christoph Hellwig wrote:
> >> f2fs_scan_devices reopens the main device since the very beginning, which
> >> has always been useless, and also means that we don't pass the right
> >> holder for the reopen, which now leads to a warning as the core super.c
> >> holder ops aren't passed in for the reopen.
> >>
> >> Fixes: 3c62be17d4f5 ("f2fs: support multiple devices")
> >> Fixes: 0718afd47f70 ("block: introduce holder ops")
> >> Signed-off-by: Christoph Hellwig <hch@lst.de>
> >> ---
> >>  fs/f2fs/super.c | 20 ++++++++------------
> >>  1 file changed, 8 insertions(+), 12 deletions(-)
> >>
> >> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> >> index ca31163da00a55..8d11d4a5ec331d 100644
> >> --- a/fs/f2fs/super.c
> >> +++ b/fs/f2fs/super.c
> >> @@ -1560,7 +1560,8 @@ static void destroy_device_list(struct f2fs_sb_info *sbi)
> >>  {
> >>  	int i;
> >>  
> >> -	for (i = 0; i < sbi->s_ndevs; i++) {
> > 
> > #ifdef CONFIG_BLK_DEV_ZONED
> > 
> >> +	kvfree(FDEV(0).blkz_seq);
> > 
> > #endif
> 
> This should not be needed since for the !CONFIG_BLK_DEV_ZONED case,
> FDEV(0).blkz_seq should always be NULL. However, what I think may be missing is
> "FDEV(0).blkz_seq = NULL;" after the kvfree() call. No ?

I was looking at a glance of this:
https://lore.kernel.org/linux-f2fs-devel/202307110542.NBAMyZxE-lkp@intel.com/T/#u

> 
> > 
> >> +	for (i = 1; i < sbi->s_ndevs; i++) {
> >>  		blkdev_put(FDEV(i).bdev, sbi->sb->s_type);
> >>  #ifdef CONFIG_BLK_DEV_ZONED
> >>  		kvfree(FDEV(i).blkz_seq);
> >> @@ -4190,16 +4191,12 @@ static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
> >>  	sbi->aligned_blksize = true;
> >>  
> >>  	for (i = 0; i < max_devices; i++) {
> >> -
> >> -		if (i > 0 && !RDEV(i).path[0])
> >> +		if (i == 0)
> >> +			FDEV(0).bdev = sbi->sb->s_bdev;
> >> +		else if (!RDEV(i).path[0])
> >>  			break;
> >>  
> >> -		if (max_devices == 1) {
> >> -			/* Single zoned block device mount */
> >> -			FDEV(0).bdev =
> >> -				blkdev_get_by_dev(sbi->sb->s_bdev->bd_dev, mode,
> >> -						  sbi->sb->s_type, NULL);
> >> -		} else {
> >> +		if (max_devices > 1) {
> >>  			/* Multi-device mount */
> >>  			memcpy(FDEV(i).path, RDEV(i).path, MAX_PATH_LEN);
> >>  			FDEV(i).total_segments =
> >> @@ -4215,10 +4212,9 @@ static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
> >>  				FDEV(i).end_blk = FDEV(i).start_blk +
> >>  					(FDEV(i).total_segments <<
> >>  					sbi->log_blocks_per_seg) - 1;
> >> +				FDEV(i).bdev = blkdev_get_by_path(FDEV(i).path,
> >> +					mode, sbi->sb->s_type, NULL);
> >>  			}
> >> -			FDEV(i).bdev = blkdev_get_by_path(FDEV(i).path, mode,
> >> -							  sbi->sb->s_type,
> >> -							  NULL);
> >>  		}
> >>  		if (IS_ERR(FDEV(i).bdev))
> >>  			return PTR_ERR(FDEV(i).bdev);
> >> -- 
> >> 2.39.2
> 
> -- 
> Damien Le Moal
> Western Digital Research


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Re: [f2fs-dev] [PATCH] f2fs: don't reopen the main block device in f2fs_scan_devices

[Damien Le Moal]

On 7/11/23 10:52, Jaegeuk Kim wrote:
>>>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
>>>> index ca31163da00a55..8d11d4a5ec331d 100644
>>>> --- a/fs/f2fs/super.c
>>>> +++ b/fs/f2fs/super.c
>>>> @@ -1560,7 +1560,8 @@ static void destroy_device_list(struct f2fs_sb_info *sbi)
>>>>  {
>>>>  	int i;
>>>>  
>>>> -	for (i = 0; i < sbi->s_ndevs; i++) {
>>>
>>> #ifdef CONFIG_BLK_DEV_ZONED
>>>
>>>> +	kvfree(FDEV(0).blkz_seq);
>>>
>>> #endif
>>
>> This should not be needed since for the !CONFIG_BLK_DEV_ZONED case,
>> FDEV(0).blkz_seq should always be NULL. However, what I think may be missing is
>> "FDEV(0).blkz_seq = NULL;" after the kvfree() call. No ?
> 
> I was looking at a glance of this:
> https://lore.kernel.org/linux-f2fs-devel/202307110542.NBAMyZxE-lkp@intel.com/T/#u

OK. Got it.
I still think that it may be safer to add the NULL affectation though.


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Re: [f2fs-dev] [PATCH] f2fs: don't reopen the main block device in f2fs_scan_devices

[Christoph Hellwig]

I think that's because it doesn't look at sbi->s_ndevs in
destroy_device_list.  Let's try the variant below, which also fixes
the buildbot warning for non-zoned configfs:

---
From 645d8dceaa97b6ee73be067495b111b15b187498 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Fri, 7 Jul 2023 10:31:49 +0200
Subject: f2fs: don't reopen the main block device in f2fs_scan_devices

f2fs_scan_devices reopens the main device since the very beginning, which
has always been useless, and also means that we don't pass the right
holder for the reopen, which now leads to a warning as the core super.c
holder ops aren't passed in for the reopen.

Fixes: 3c62be17d4f5 ("f2fs: support multiple devices")
Fixes: 0718afd47f70 ("block: introduce holder ops")
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/blk-flush.c |  2 +-
 fs/f2fs/super.c   | 20 ++++++++------------
 2 files changed, 9 insertions(+), 13 deletions(-)

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index ca31163da00a55..30883beb750a59 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1561,7 +1561,8 @@ static void destroy_device_list(struct f2fs_sb_info *sbi)
 	int i;
 
 	for (i = 0; i < sbi->s_ndevs; i++) {
-		blkdev_put(FDEV(i).bdev, sbi->sb->s_type);
+		if (i > 0)
+			blkdev_put(FDEV(i).bdev, sbi->sb->s_type);
 #ifdef CONFIG_BLK_DEV_ZONED
 		kvfree(FDEV(i).blkz_seq);
 #endif
@@ -4190,16 +4191,12 @@ static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
 	sbi->aligned_blksize = true;
 
 	for (i = 0; i < max_devices; i++) {
-
-		if (i > 0 && !RDEV(i).path[0])
+		if (i == 0)
+			FDEV(0).bdev = sbi->sb->s_bdev;
+		else if (!RDEV(i).path[0])
 			break;
 
-		if (max_devices == 1) {
-			/* Single zoned block device mount */
-			FDEV(0).bdev =
-				blkdev_get_by_dev(sbi->sb->s_bdev->bd_dev, mode,
-						  sbi->sb->s_type, NULL);
-		} else {
+		if (max_devices > 1) {
 			/* Multi-device mount */
 			memcpy(FDEV(i).path, RDEV(i).path, MAX_PATH_LEN);
 			FDEV(i).total_segments =
@@ -4215,10 +4212,9 @@ static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
 				FDEV(i).end_blk = FDEV(i).start_blk +
 					(FDEV(i).total_segments <<
 					sbi->log_blocks_per_seg) - 1;
+				FDEV(i).bdev = blkdev_get_by_path(FDEV(i).path,
+					mode, sbi->sb->s_type, NULL);
 			}
-			FDEV(i).bdev = blkdev_get_by_path(FDEV(i).path, mode,
-							  sbi->sb->s_type,
-							  NULL);
 		}
 		if (IS_ERR(FDEV(i).bdev))
 			return PTR_ERR(FDEV(i).bdev);
-- 
2.39.2



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Re: [f2fs-dev] [PATCH] f2fs: don't reopen the main block device in f2fs_scan_devices

[Hannes Reinecke]

On 7/11/23 07:01, Christoph Hellwig wrote:
> I think that's because it doesn't look at sbi->s_ndevs in
> destroy_device_list.  Let's try the variant below, which also fixes
> the buildbot warning for non-zoned configfs:
> 
> ---
>  From 645d8dceaa97b6ee73be067495b111b15b187498 Mon Sep 17 00:00:00 2001
> From: Christoph Hellwig <hch@lst.de>
> Date: Fri, 7 Jul 2023 10:31:49 +0200
> Subject: f2fs: don't reopen the main block device in f2fs_scan_devices
> 
> f2fs_scan_devices reopens the main device since the very beginning, which
> has always been useless, and also means that we don't pass the right
> holder for the reopen, which now leads to a warning as the core super.c
> holder ops aren't passed in for the reopen.
> 
> Fixes: 3c62be17d4f5 ("f2fs: support multiple devices")
> Fixes: 0718afd47f70 ("block: introduce holder ops")
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>   block/blk-flush.c |  2 +-
>   fs/f2fs/super.c   | 20 ++++++++------------
>   2 files changed, 9 insertions(+), 13 deletions(-)
> 
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index ca31163da00a55..30883beb750a59 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -1561,7 +1561,8 @@ static void destroy_device_list(struct f2fs_sb_info *sbi)
>   	int i;
>   
>   	for (i = 0; i < sbi->s_ndevs; i++) {
> -		blkdev_put(FDEV(i).bdev, sbi->sb->s_type);
> +		if (i > 0)
> +			blkdev_put(FDEV(i).bdev, sbi->sb->s_type);
You could have started the loop at '1', and avoid the curious 'if' 
clause ...

>   #ifdef CONFIG_BLK_DEV_ZONED
>   		kvfree(FDEV(i).blkz_seq);
>   #endif
> @@ -4190,16 +4191,12 @@ static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
>   	sbi->aligned_blksize = true;
>   
>   	for (i = 0; i < max_devices; i++) {
> -
> -		if (i > 0 && !RDEV(i).path[0])
> +		if (i == 0)
> +			FDEV(0).bdev = sbi->sb->s_bdev;
> +		else if (!RDEV(i).path[0])
>   			break;
>   
> -		if (max_devices == 1) {
> -			/* Single zoned block device mount */
> -			FDEV(0).bdev =
> -				blkdev_get_by_dev(sbi->sb->s_bdev->bd_dev, mode,
> -						  sbi->sb->s_type, NULL);
> -		} else {
> +		if (max_devices > 1) {
>   			/* Multi-device mount */
>   			memcpy(FDEV(i).path, RDEV(i).path, MAX_PATH_LEN);
>   			FDEV(i).total_segments =
Similar here; wouldn't it be better to unroll the loop, and have the 
check for 'max_devices' outside of the loop?
Then the loop can be coded for the 'max_device > 1' case only, and avoid 
all the special casing in the loop ...

> @@ -4215,10 +4212,9 @@ static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
>   				FDEV(i).end_blk = FDEV(i).start_blk +
>   					(FDEV(i).total_segments <<
>   					sbi->log_blocks_per_seg) - 1;
> +				FDEV(i).bdev = blkdev_get_by_path(FDEV(i).path,
> +					mode, sbi->sb->s_type, NULL);
>   			}
> -			FDEV(i).bdev = blkdev_get_by_path(FDEV(i).path, mode,
> -							  sbi->sb->s_type,
> -							  NULL);
>   		}
>   		if (IS_ERR(FDEV(i).bdev))
>   			return PTR_ERR(FDEV(i).bdev);

Cheers,

Hannes
-- 
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hare@suse.de                              +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Ivo Totev, Andrew
Myers, Andrew McDonald, Martje Boudien Moerman



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Re: [f2fs-dev] [PATCH] f2fs: don't reopen the main block device in f2fs_scan_devices

[Christoph Hellwig]

On Tue, Jul 11, 2023 at 08:19:50AM +0200, Hannes Reinecke wrote:
>>     	for (i = 0; i < sbi->s_ndevs; i++) {
>> -		blkdev_put(FDEV(i).bdev, sbi->sb->s_type);
>> +		if (i > 0)
>> +			blkdev_put(FDEV(i).bdev, sbi->sb->s_type);
> You could have started the loop at '1', and avoid the curious 'if' clause 

That's what the previous version did, which caused a NULL pointer
dereference discussed in this thread, as well as a compile error for
non-zoned builds..



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Re: [f2fs-dev] [PATCH] f2fs: don't reopen the main block device in f2fs_scan_devices

[Jaegeuk Kim]

On 07/11, Christoph Hellwig wrote:
> I think that's because it doesn't look at sbi->s_ndevs in
> destroy_device_list.  Let's try the variant below, which also fixes
> the buildbot warning for non-zoned configfs:

Thanks. At a glance, this looks better. Let me give it a try.

> 
> ---
> >From 645d8dceaa97b6ee73be067495b111b15b187498 Mon Sep 17 00:00:00 2001
> From: Christoph Hellwig <hch@lst.de>
> Date: Fri, 7 Jul 2023 10:31:49 +0200
> Subject: f2fs: don't reopen the main block device in f2fs_scan_devices
> 
> f2fs_scan_devices reopens the main device since the very beginning, which
> has always been useless, and also means that we don't pass the right
> holder for the reopen, which now leads to a warning as the core super.c
> holder ops aren't passed in for the reopen.
> 
> Fixes: 3c62be17d4f5 ("f2fs: support multiple devices")
> Fixes: 0718afd47f70 ("block: introduce holder ops")
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  block/blk-flush.c |  2 +-
>  fs/f2fs/super.c   | 20 ++++++++------------
>  2 files changed, 9 insertions(+), 13 deletions(-)
> 
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index ca31163da00a55..30883beb750a59 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -1561,7 +1561,8 @@ static void destroy_device_list(struct f2fs_sb_info *sbi)
>  	int i;
>  
>  	for (i = 0; i < sbi->s_ndevs; i++) {
> -		blkdev_put(FDEV(i).bdev, sbi->sb->s_type);
> +		if (i > 0)
> +			blkdev_put(FDEV(i).bdev, sbi->sb->s_type);
>  #ifdef CONFIG_BLK_DEV_ZONED
>  		kvfree(FDEV(i).blkz_seq);
>  #endif
> @@ -4190,16 +4191,12 @@ static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
>  	sbi->aligned_blksize = true;
>  
>  	for (i = 0; i < max_devices; i++) {
> -
> -		if (i > 0 && !RDEV(i).path[0])
> +		if (i == 0)
> +			FDEV(0).bdev = sbi->sb->s_bdev;
> +		else if (!RDEV(i).path[0])
>  			break;
>  
> -		if (max_devices == 1) {
> -			/* Single zoned block device mount */
> -			FDEV(0).bdev =
> -				blkdev_get_by_dev(sbi->sb->s_bdev->bd_dev, mode,
> -						  sbi->sb->s_type, NULL);
> -		} else {
> +		if (max_devices > 1) {
>  			/* Multi-device mount */
>  			memcpy(FDEV(i).path, RDEV(i).path, MAX_PATH_LEN);
>  			FDEV(i).total_segments =
> @@ -4215,10 +4212,9 @@ static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
>  				FDEV(i).end_blk = FDEV(i).start_blk +
>  					(FDEV(i).total_segments <<
>  					sbi->log_blocks_per_seg) - 1;
> +				FDEV(i).bdev = blkdev_get_by_path(FDEV(i).path,
> +					mode, sbi->sb->s_type, NULL);
>  			}
> -			FDEV(i).bdev = blkdev_get_by_path(FDEV(i).path, mode,
> -							  sbi->sb->s_type,
> -							  NULL);
>  		}
>  		if (IS_ERR(FDEV(i).bdev))
>  			return PTR_ERR(FDEV(i).bdev);
> -- 
> 2.39.2


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Re: [f2fs-dev] [PATCH] f2fs: don't reopen the main block device in f2fs_scan_devices

[Chao Yu]

On 2023/7/11 13:01, Christoph Hellwig wrote:
> I think that's because it doesn't look at sbi->s_ndevs in
> destroy_device_list.  Let's try the variant below, which also fixes
> the buildbot warning for non-zoned configfs:
> 
> ---
>  From 645d8dceaa97b6ee73be067495b111b15b187498 Mon Sep 17 00:00:00 2001
> From: Christoph Hellwig <hch@lst.de>
> Date: Fri, 7 Jul 2023 10:31:49 +0200
> Subject: f2fs: don't reopen the main block device in f2fs_scan_devices
> 
> f2fs_scan_devices reopens the main device since the very beginning, which
> has always been useless, and also means that we don't pass the right
> holder for the reopen, which now leads to a warning as the core super.c
> holder ops aren't passed in for the reopen.
> 
> Fixes: 3c62be17d4f5 ("f2fs: support multiple devices")
> Fixes: 0718afd47f70 ("block: introduce holder ops")
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Reviewed-by: Chao Yu <chao@kernel.org>

Thanks,


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