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Date: Mon, 21 Mar 2011 20:35:20 +0100 (CET)
From: Lukas Czerner <lczerner@...hat.com>
To: "Theodore Ts'o" <tytso@....edu>
cc: linux-ext4@...r.kernel.org
Subject: Re: [PATCH, RFC 01/12] ext4: read-only support for bigalloc file
systems
On Sat, 19 Mar 2011, Theodore Ts'o wrote:
> This adds supports for bigalloc file systems. It teaches the mount
> code just enough about bigalloc superblock fields that it will mount
> the file system without freaking out that the number of blocks per
> group is too big.
>
> Signed-off-by: "Theodore Ts'o" <tytso@....edu>
> ---
> fs/ext4/ext4.h | 18 ++++++++++++++--
> fs/ext4/super.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++-------
> 2 files changed, 65 insertions(+), 11 deletions(-)
>
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 3aa0b72..94a7a7b 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -231,12 +231,16 @@ struct ext4_io_submit {
> #define EXT4_MAX_BLOCK_LOG_SIZE 16
> #ifdef __KERNEL__
> # define EXT4_BLOCK_SIZE(s) ((s)->s_blocksize)
> +# define EXT4_CLUSTER_SIZE(s) (EXT4_SB(s)->s_clustersize)
> #else
> +# define EXT2_CLUSTER_SIZE(s) (EXT2_MIN_BLOCK_SIZE << \
> + (s)->s_log_cluster_size)
> # define EXT4_BLOCK_SIZE(s) (EXT4_MIN_BLOCK_SIZE << (s)->s_log_block_size)
> #endif
> #define EXT4_ADDR_PER_BLOCK(s) (EXT4_BLOCK_SIZE(s) / sizeof(__u32))
> #ifdef __KERNEL__
> # define EXT4_BLOCK_SIZE_BITS(s) ((s)->s_blocksize_bits)
> +# define EXT4_CLUSTER_SIZE_BITS(s) (EXT4_SB(s)->s_clustersize_bits)
> #else
> # define EXT4_BLOCK_SIZE_BITS(s) ((s)->s_log_block_size + 10)
> #endif
> @@ -302,6 +306,7 @@ struct flex_groups {
> #define EXT4_DESC_SIZE(s) (EXT4_SB(s)->s_desc_size)
> #ifdef __KERNEL__
> # define EXT4_BLOCKS_PER_GROUP(s) (EXT4_SB(s)->s_blocks_per_group)
> +# define EXT4_CLUSTERS_PER_GROUP(s) (EXT4_SB(s)->s_clusters_per_group)
> # define EXT4_DESC_PER_BLOCK(s) (EXT4_SB(s)->s_desc_per_block)
> # define EXT4_INODES_PER_GROUP(s) (EXT4_SB(s)->s_inodes_per_group)
> # define EXT4_DESC_PER_BLOCK_BITS(s) (EXT4_SB(s)->s_desc_per_block_bits)
> @@ -957,9 +962,9 @@ struct ext4_super_block {
> /*10*/ __le32 s_free_inodes_count; /* Free inodes count */
> __le32 s_first_data_block; /* First Data Block */
> __le32 s_log_block_size; /* Block size */
> - __le32 s_obso_log_frag_size; /* Obsoleted fragment size */
> + __le32 s_log_cluster_size; /* Allocation cluster size */
> /*20*/ __le32 s_blocks_per_group; /* # Blocks per group */
> - __le32 s_obso_frags_per_group; /* Obsoleted fragments per group */
> + __le32 s_clusters_per_group; /* # Clusters per group */
> __le32 s_inodes_per_group; /* # Inodes per group */
> __le32 s_mtime; /* Mount time */
> /*30*/ __le32 s_wtime; /* Write time */
> @@ -1055,7 +1060,10 @@ struct ext4_super_block {
> __u8 s_last_error_func[32]; /* function where the error happened */
> #define EXT4_S_ERR_END offsetof(struct ext4_super_block, s_mount_opts)
> __u8 s_mount_opts[64];
> - __le32 s_reserved[112]; /* Padding to the end of the block */
> + __le32 s_usr_quota_inum; /* inode for tracking user quota */
> + __le32 s_grp_quota_inum; /* inode for tracking group quota */
> + __le32 s_overhead_blocks; /* overhead blocks/clusters in fs */
> + __le32 s_reserved[109]; /* Padding to the end of the block */
> };
>
> #define EXT4_S_ERR_LEN (EXT4_S_ERR_END - EXT4_S_ERR_START)
> @@ -1075,6 +1083,7 @@ struct ext4_sb_info {
> unsigned long s_desc_size; /* Size of a group descriptor in bytes */
> unsigned long s_inodes_per_block;/* Number of inodes per block */
> unsigned long s_blocks_per_group;/* Number of blocks in a group */
> + unsigned long s_clusters_per_group; /* Number of clusters in a group */
> unsigned long s_inodes_per_group;/* Number of inodes in a group */
> unsigned long s_itb_per_group; /* Number of inode table blocks per group */
> unsigned long s_gdb_count; /* Number of group descriptor blocks */
> @@ -1083,6 +1092,8 @@ struct ext4_sb_info {
> ext4_group_t s_blockfile_groups;/* Groups acceptable for non-extent files */
> unsigned long s_overhead_last; /* Last calculated overhead */
> unsigned long s_blocks_last; /* Last seen block count */
> + unsigned int s_cluster_ratio; /* Number of blocks per group */
> + unsigned int s_cluster_bits; /* log2 of s_cluster_ratio */
> loff_t s_bitmap_maxbytes; /* max bytes for bitmap files */
> struct buffer_head * s_sbh; /* Buffer containing the super block */
> struct ext4_super_block *s_es; /* Pointer to the super block in the buffer */
> @@ -1338,6 +1349,7 @@ static inline void ext4_clear_state_flags(struct ext4_inode_info *ei)
> #define EXT4_FEATURE_RO_COMPAT_GDT_CSUM 0x0010
> #define EXT4_FEATURE_RO_COMPAT_DIR_NLINK 0x0020
> #define EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE 0x0040
> +#define EXT4_FEATURE_RO_COMPAT_BIGALLOC 0x0200
>
> #define EXT4_FEATURE_INCOMPAT_COMPRESSION 0x0001
> #define EXT4_FEATURE_INCOMPAT_FILETYPE 0x0002
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index b357c27..7273728 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1875,7 +1875,7 @@ static int ext4_setup_super(struct super_block *sb, struct ext4_super_block *es,
> res = MS_RDONLY;
> }
> if (read_only)
> - return res;
> + goto done;
> if (!(sbi->s_mount_state & EXT4_VALID_FS))
> ext4_msg(sb, KERN_WARNING, "warning: mounting unchecked fs, "
> "running e2fsck is recommended");
> @@ -1906,6 +1906,7 @@ static int ext4_setup_super(struct super_block *sb, struct ext4_super_block *es,
> EXT4_SET_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER);
>
> ext4_commit_super(sb, 1);
> +done:
> if (test_opt(sb, DEBUG))
> printk(KERN_INFO "[EXT4 FS bs=%lu, gc=%u, "
> "bpg=%lu, ipg=%lu, mo=%04x, mo2=%04x]\n",
Maybe this is a bit nitpicky, but should not this be rather done in
separate commit as it has nothing to do with bigalloc ?
> @@ -3022,10 +3023,10 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
> char *cp;
> const char *descr;
> int ret = -ENOMEM;
> - int blocksize;
> + int blocksize, clustersize;
> unsigned int db_count;
> unsigned int i;
> - int needs_recovery, has_huge_files;
> + int needs_recovery, has_huge_files, has_bigalloc;
> __u64 blocks_count;
> int err;
> unsigned int journal_ioprio = DEFAULT_JOURNAL_IOPRIO;
> @@ -3276,12 +3277,53 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
> sb->s_dirt = 1;
> }
>
> - if (sbi->s_blocks_per_group > blocksize * 8) {
> - ext4_msg(sb, KERN_ERR,
> - "#blocks per group too big: %lu",
> - sbi->s_blocks_per_group);
> - goto failed_mount;
> + /* Handle clustersize */
> + clustersize = BLOCK_SIZE << le32_to_cpu(es->s_log_cluster_size);
> + has_bigalloc = EXT4_HAS_RO_COMPAT_FEATURE(sb,
> + EXT4_FEATURE_RO_COMPAT_BIGALLOC);
> + if (has_bigalloc) {
> + if (clustersize < blocksize) {
> + ext4_msg(sb, KERN_ERR,
> + "cluster size (%d) smaller than "
> + "block size (%d)", clustersize, blocksize);
> + goto failed_mount;
> + }
> + sbi->s_cluster_bits = le32_to_cpu(es->s_log_cluster_size) -
> + le32_to_cpu(es->s_log_block_size);
> + sbi->s_clusters_per_group =
> + le32_to_cpu(es->s_clusters_per_group);
> + if (sbi->s_clusters_per_group > blocksize * 8) {
> + ext4_msg(sb, KERN_ERR,
> + "#clusters per group too big: %lu",
> + sbi->s_clusters_per_group);
> + goto failed_mount;
> + }
> + if (sbi->s_blocks_per_group !=
> + (sbi->s_clusters_per_group * (clustersize / blocksize))) {
> + ext4_msg(sb, KERN_ERR, "blocks per group (%lu) and "
> + "clusters per group (%lu) inconsistent",
> + sbi->s_blocks_per_group,
> + sbi->s_clusters_per_group);
> + goto failed_mount;
> + }
> + } else {
> + if (clustersize != blocksize) {
> + ext4_warning(sb, "fragment/cluster size (%d) != "
> + "block size (%d)", clustersize,
> + blocksize);
> + clustersize = blocksize;
I wonder if we should continue at this point, because something
definitely went wrong as it has not biballoc feature but yet
s_log_cluster_size does not match s_log_block_size which means
definitely corruption or an error somewhere.
> + }
> + if (sbi->s_blocks_per_group > blocksize * 8) {
> + ext4_msg(sb, KERN_ERR,
> + "#blocks per group too big: %lu",
> + sbi->s_blocks_per_group);
> + goto failed_mount;
> + }
> + sbi->s_clusters_per_group = sbi->s_blocks_per_group;
> + sbi->s_cluster_bits = 0;
> }
> + sbi->s_cluster_ratio = clustersize / blocksize;
> +
> if (sbi->s_inodes_per_group > blocksize * 8) {
> ext4_msg(sb, KERN_ERR,
> "#inodes per group too big: %lu",
>
Thanks!
-Lukas
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