| Message ID | 20250327140613.25178-4-James.Bottomley@HansenPartnership.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | vfs freeze/thaw on suspend/resume | expand |
On Thu, Mar 27, 2025 at 10:06:12AM -0400, James Bottomley wrote: > Originally proposed by Amir as an extract from the android kernel: > > https://lore.kernel.org/linux-fsdevel/CAA2m6vfatWKS1CQFpaRbii2AXiZFvQUjVvYhGxWTSpz+2rxDyg@mail.gmail.com/ > > Since suspend/resume requires a reverse iterator, I'm dusting it off. > > Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com> > --- > fs/super.c | 48 +++++++++++++++++++++++++++++------------------- > 1 file changed, 29 insertions(+), 19 deletions(-) > > diff --git a/fs/super.c b/fs/super.c > index 5a7db4a556e3..76785509d906 100644 > --- a/fs/super.c > +++ b/fs/super.c > @@ -887,28 +887,38 @@ void drop_super_exclusive(struct super_block *sb) > } > EXPORT_SYMBOL(drop_super_exclusive); > > +#define ITERATE_SUPERS(f, rev) \ I'm not fond of the macro magic here. I've taken some of your patches and massaging them.
On Fri, 2025-03-28 at 12:56 +0100, Christian Brauner wrote: > On Thu, Mar 27, 2025 at 10:06:12AM -0400, James Bottomley wrote: > > Originally proposed by Amir as an extract from the android kernel: > > > > https://lore.kernel.org/linux-fsdevel/CAA2m6vfatWKS1CQFpaRbii2AXiZFvQUjVvYhGxWTSpz+2rxDyg@mail.gmail.com/ > > > > Since suspend/resume requires a reverse iterator, I'm dusting it > > off. > > > > Signed-off-by: James Bottomley > > <James.Bottomley@HansenPartnership.com> > > --- > > fs/super.c | 48 +++++++++++++++++++++++++++++------------------- > > 1 file changed, 29 insertions(+), 19 deletions(-) > > > > diff --git a/fs/super.c b/fs/super.c > > index 5a7db4a556e3..76785509d906 100644 > > --- a/fs/super.c > > +++ b/fs/super.c > > @@ -887,28 +887,38 @@ void drop_super_exclusive(struct super_block > > *sb) > > } > > EXPORT_SYMBOL(drop_super_exclusive); > > > > +#define ITERATE_SUPERS(f, rev) \ > > I'm not fond of the macro magic here. > I've taken some of your patches and massaging them. I'm not either, so if you have an alternative, I'm all ears. The problem I had is that list_for_each_entry() and _reverse are designed to take a code block, so it's very difficult to swap one for the other without macroizing. The internal logic is complex enough that I didn't want to duplicate it. Regards, James
diff --git a/fs/super.c b/fs/super.c index 5a7db4a556e3..76785509d906 100644 --- a/fs/super.c +++ b/fs/super.c @@ -887,28 +887,38 @@ void drop_super_exclusive(struct super_block *sb) } EXPORT_SYMBOL(drop_super_exclusive); +#define ITERATE_SUPERS(f, rev) \ + struct super_block *sb, *p = NULL; \ + \ + spin_lock(&sb_lock); \ + \ + list_for_each_entry##rev(sb, &super_blocks, s_list) { \ + if (super_flags(sb, SB_DYING)) \ + continue; \ + sb->s_count++; \ + spin_unlock(&sb_lock); \ + \ + f(sb); \ + \ + spin_lock(&sb_lock); \ + if (p) \ + __put_super(p); \ + p = sb; \ + } \ + if (p) \ + __put_super(p); \ + spin_unlock(&sb_lock); + static void __iterate_supers(void (*f)(struct super_block *)) { - struct super_block *sb, *p = NULL; - - spin_lock(&sb_lock); - list_for_each_entry(sb, &super_blocks, s_list) { - if (super_flags(sb, SB_DYING)) - continue; - sb->s_count++; - spin_unlock(&sb_lock); - - f(sb); + ITERATE_SUPERS(f,) +} - spin_lock(&sb_lock); - if (p) - __put_super(p); - p = sb; - } - if (p) - __put_super(p); - spin_unlock(&sb_lock); +static void __iterate_supers_rev(void (*f)(struct super_block *)) +{ + ITERATE_SUPERS(f, _reverse) } + /** * iterate_supers - call function for all active superblocks * @f: function to call @@ -1132,7 +1142,7 @@ static void do_emergency_remount_callback(struct super_block *sb) static void do_emergency_remount(struct work_struct *work) { - __iterate_supers(do_emergency_remount_callback); + __iterate_supers_rev(do_emergency_remount_callback); kfree(work); printk("Emergency Remount complete\n"); }
Originally proposed by Amir as an extract from the android kernel: https://lore.kernel.org/linux-fsdevel/CAA2m6vfatWKS1CQFpaRbii2AXiZFvQUjVvYhGxWTSpz+2rxDyg@mail.gmail.com/ Since suspend/resume requires a reverse iterator, I'm dusting it off. Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com> --- fs/super.c | 48 +++++++++++++++++++++++++++++------------------- 1 file changed, 29 insertions(+), 19 deletions(-)