| Message ID | 1482928596-115155-1-git-send-email-colyli@suse.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Andrew, This fix is verified by Nong Li, it works well in all three conditions, - CONFIG_ROMFS_ON_BLOCK defined - CONFIG_ROMFS_ON_BLOCK undefined and CONFIG_ROMFS_ON_MTD defined - both CONFIG_ROMFS_ON_BLOCK and CONFIG_ROMFS_ON_MTD undefined Last time the original patch was picked by you, could you please take care it again this time. Thanks in advance. Coly Li On 2016/12/28 下午8:36, Coly Li wrote: > 'Commit 8a59f5d25265 ("fs/romfs: return f_fsid for statfs(2)")' generates > a 64bit id from sb->s_bdev->bd_dev. This is only correct when romfs is > defined with CONFIG_ROMFS_ON_BLOCK. If romfs is only defined with > CONFIG_ROMFS_ON_MTD, sb->s_bdev is NULL, referencing sb->s_bdev->bd_dev > will triger an oops. > > Richard Weinberger points out that when CONFIG_ROMFS_BACKED_BY_BOTH=y, > both CONFIG_ROMFS_ON_BLOCK and CONFIG_ROMFS_ON_MTD are defined. Therefore > when calling huge_encode_dev() to generate a 64bit id, I use the follow > order to choose parameter, > - CONFIG_ROMFS_ON_BLOCK defined > use sb->s_bdev->bd_dev > - CONFIG_ROMFS_ON_BLOCK undefined and CONFIG_ROMFS_ON_MTD defined > use sb->s_dev when, > - both CONFIG_ROMFS_ON_BLOCK and CONFIG_ROMFS_ON_MTD undefined > leave id as 0 > > When CONFIG_ROMFS_ON_MTD is defined and sb->s_mtd is not NULL, sb->s_dev > is set to a device ID generated by MTD_BLOCK_MAJOR and mtd index, otherwise > sb->s_dev is 0. > > This is a try-best effort to generate a uniq file system ID, if all the > above conditions are not meet, f_fsid of this romfs instance will be 0. > Generally only one romfs can be built on single MTD block device, this > method is enough to identify multiple romfs instances in a computer. > > Signed-off-by: Coly Li <colyli@suse.de> > Reported-by: Nong Li <nongli1031@gmail.com> > Tested-by: Nong Li <nongli1031@gmail.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Richard Weinberger <richard.weinberger@gmail.com> > Cc: linux-fsdevel@vger.kernel.org > Cc: linux-mtd@lists.infradead.org > --- > fs/romfs/super.c | 23 ++++++++++++++++++++++- > 1 file changed, 22 insertions(+), 1 deletion(-) > > diff --git a/fs/romfs/super.c b/fs/romfs/super.c > index d0f8a38..0186fe6 100644 > --- a/fs/romfs/super.c > +++ b/fs/romfs/super.c > @@ -74,6 +74,7 @@ > #include <linux/highmem.h> > #include <linux/pagemap.h> > #include <linux/uaccess.h> > +#include <linux/major.h> > #include "internal.h" > > static struct kmem_cache *romfs_inode_cachep; > @@ -416,7 +417,22 @@ static void romfs_destroy_inode(struct inode *inode) > static int romfs_statfs(struct dentry *dentry, struct kstatfs *buf) > { > struct super_block *sb = dentry->d_sb; > - u64 id = huge_encode_dev(sb->s_bdev->bd_dev); > + u64 id = 0; > + > + /* When calling huge_encode_dev(), > + * use sb->s_bdev->bd_dev when, > + * - CONFIG_ROMFS_ON_BLOCK defined > + * use sb->s_dev when, > + * - CONFIG_ROMFS_ON_BLOCK undefined and > + * - CONFIG_ROMFS_ON_MTD defined > + * leave id as 0 when, > + * - CONFIG_ROMFS_ON_BLOCK undefined and > + * - CONFIG_ROMFS_ON_MTD undefined > + */ > + if (sb->s_bdev) > + id = huge_encode_dev(sb->s_bdev->bd_dev); > + else if (sb->s_dev) > + id = huge_encode_dev(sb->s_dev); > > buf->f_type = ROMFS_MAGIC; > buf->f_namelen = ROMFS_MAXFN; > @@ -489,6 +505,11 @@ static int romfs_fill_super(struct super_block *sb, void *data, int silent) > sb->s_flags |= MS_RDONLY | MS_NOATIME; > sb->s_op = &romfs_super_ops; > > +#ifdef CONFIG_ROMFS_ON_MTD > + /* Use same dev ID from the underlying mtdblock device */ > + if (sb->s_mtd) > + sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, sb->s_mtd->index); > +#endif > /* read the image superblock and check it */ > rsb = kmalloc(512, GFP_KERNEL); > if (!rsb) >
diff --git a/fs/romfs/super.c b/fs/romfs/super.c index d0f8a38..0186fe6 100644 --- a/fs/romfs/super.c +++ b/fs/romfs/super.c @@ -74,6 +74,7 @@ #include <linux/highmem.h> #include <linux/pagemap.h> #include <linux/uaccess.h> +#include <linux/major.h> #include "internal.h" static struct kmem_cache *romfs_inode_cachep; @@ -416,7 +417,22 @@ static void romfs_destroy_inode(struct inode *inode) static int romfs_statfs(struct dentry *dentry, struct kstatfs *buf) { struct super_block *sb = dentry->d_sb; - u64 id = huge_encode_dev(sb->s_bdev->bd_dev); + u64 id = 0; + + /* When calling huge_encode_dev(), + * use sb->s_bdev->bd_dev when, + * - CONFIG_ROMFS_ON_BLOCK defined + * use sb->s_dev when, + * - CONFIG_ROMFS_ON_BLOCK undefined and + * - CONFIG_ROMFS_ON_MTD defined + * leave id as 0 when, + * - CONFIG_ROMFS_ON_BLOCK undefined and + * - CONFIG_ROMFS_ON_MTD undefined + */ + if (sb->s_bdev) + id = huge_encode_dev(sb->s_bdev->bd_dev); + else if (sb->s_dev) + id = huge_encode_dev(sb->s_dev); buf->f_type = ROMFS_MAGIC; buf->f_namelen = ROMFS_MAXFN; @@ -489,6 +505,11 @@ static int romfs_fill_super(struct super_block *sb, void *data, int silent) sb->s_flags |= MS_RDONLY | MS_NOATIME; sb->s_op = &romfs_super_ops; +#ifdef CONFIG_ROMFS_ON_MTD + /* Use same dev ID from the underlying mtdblock device */ + if (sb->s_mtd) + sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, sb->s_mtd->index); +#endif /* read the image superblock and check it */ rsb = kmalloc(512, GFP_KERNEL); if (!rsb)
'Commit 8a59f5d25265 ("fs/romfs: return f_fsid for statfs(2)")' generates a 64bit id from sb->s_bdev->bd_dev. This is only correct when romfs is defined with CONFIG_ROMFS_ON_BLOCK. If romfs is only defined with CONFIG_ROMFS_ON_MTD, sb->s_bdev is NULL, referencing sb->s_bdev->bd_dev will triger an oops. Richard Weinberger points out that when CONFIG_ROMFS_BACKED_BY_BOTH=y, both CONFIG_ROMFS_ON_BLOCK and CONFIG_ROMFS_ON_MTD are defined. Therefore when calling huge_encode_dev() to generate a 64bit id, I use the follow order to choose parameter, - CONFIG_ROMFS_ON_BLOCK defined use sb->s_bdev->bd_dev - CONFIG_ROMFS_ON_BLOCK undefined and CONFIG_ROMFS_ON_MTD defined use sb->s_dev when, - both CONFIG_ROMFS_ON_BLOCK and CONFIG_ROMFS_ON_MTD undefined leave id as 0 When CONFIG_ROMFS_ON_MTD is defined and sb->s_mtd is not NULL, sb->s_dev is set to a device ID generated by MTD_BLOCK_MAJOR and mtd index, otherwise sb->s_dev is 0. This is a try-best effort to generate a uniq file system ID, if all the above conditions are not meet, f_fsid of this romfs instance will be 0. Generally only one romfs can be built on single MTD block device, this method is enough to identify multiple romfs instances in a computer. Signed-off-by: Coly Li <colyli@suse.de> Reported-by: Nong Li <nongli1031@gmail.com> Tested-by: Nong Li <nongli1031@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Richard Weinberger <richard.weinberger@gmail.com> Cc: linux-fsdevel@vger.kernel.org Cc: linux-mtd@lists.infradead.org --- fs/romfs/super.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-)