Skip to content

Commit

Permalink
ext2: Add ext2_sb_info s_lock spinlock
Browse files Browse the repository at this point in the history 
Add a spinlock that protects against concurrent modifications of
s_mount_state, s_blocks_last, s_overhead_last and the content of the
superblock's buffer pointed to by sbi->s_es. The spinlock is now used in
ext2_xattr_update_super_block() which was setting the
EXT2_FEATURE_COMPAT_EXT_ATTR flag on the superblock without protection
before. Likewise the spinlock is used in ext2_show_options() to have a
consistent view of the mount options.

This is a preparation patch for removing the BKL from ext2 in the next
patch.

Signed-off-by: Jan Blunck <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: OGAWA Hirofumi <[email protected]>
Signed-off-by: Jan Kara <[email protected]>
  • Loading branch information
@jankara
Jan Blunck authored and jankara committed May 21, 2010
1 parent 4c96a68 commit c15271f
Show file tree
Hide file tree
Showing 4 changed files with 39 additions and 1 deletion.
2 changes: 2 additions & 0 deletions fs/ext2/inode.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1407,9 +1407,11 @@ static int __ext2_write_inode(struct inode *inode, int do_sync)
* created, add a flag to the superblock.
*/
lock_kernel();
spin_lock(&EXT2_SB(sb)->s_lock);
ext2_update_dynamic_rev(sb);
EXT2_SET_RO_COMPAT_FEATURE(sb,
EXT2_FEATURE_RO_COMPAT_LARGE_FILE);
spin_unlock(&EXT2_SB(sb)->s_lock);
unlock_kernel();
ext2_write_super(sb);
}
Expand Down
27 changes: 26 additions & 1 deletion fs/ext2/super.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -52,8 +52,10 @@ void ext2_error (struct super_block * sb, const char * function,
struct ext2_super_block *es = sbi->s_es;

if (!(sb->s_flags & MS_RDONLY)) {
spin_lock(&sbi->s_lock);
sbi->s_mount_state |= EXT2_ERROR_FS;
es->s_state |= cpu_to_le16(EXT2_ERROR_FS);
spin_unlock(&sbi->s_lock);
ext2_sync_super(sb, es, 1);
}

Expand Down Expand Up @@ -84,6 +86,9 @@ void ext2_msg(struct super_block *sb, const char *prefix,
va_end(args);
}

/*
* This must be called with sbi->s_lock held.
*/
void ext2_update_dynamic_rev(struct super_block *sb)
{
struct ext2_super_block *es = EXT2_SB(sb)->s_es;
Expand Down Expand Up @@ -124,7 +129,9 @@ static void ext2_put_super (struct super_block * sb)
if (!(sb->s_flags & MS_RDONLY)) {
struct ext2_super_block *es = sbi->s_es;

spin_lock(&sbi->s_lock);
es->s_state = cpu_to_le16(sbi->s_mount_state);
spin_unlock(&sbi->s_lock);
ext2_sync_super(sb, es, 1);
}
db_count = sbi->s_gdb_count;
Expand Down Expand Up @@ -209,6 +216,7 @@ static int ext2_show_options(struct seq_file *seq, struct vfsmount *vfs)
struct ext2_super_block *es = sbi->s_es;
unsigned long def_mount_opts;

spin_lock(&sbi->s_lock);
def_mount_opts = le32_to_cpu(es->s_default_mount_opts);

if (sbi->s_sb_block != 1)
Expand Down Expand Up @@ -281,6 +289,7 @@ static int ext2_show_options(struct seq_file *seq, struct vfsmount *vfs)
if (!test_opt(sb, RESERVATION))
seq_puts(seq, ",noreservation");

spin_unlock(&sbi->s_lock);
return 0;
}

Expand Down Expand Up @@ -766,6 +775,8 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
sb->s_fs_info = sbi;
sbi->s_sb_block = sb_block;

spin_lock_init(&sbi->s_lock);

/*
* See what the current blocksize for the device is, and
* use that as the blocksize. Otherwise (or if the blocksize
Expand Down Expand Up @@ -1132,9 +1143,12 @@ static void ext2_sync_super(struct super_block *sb, struct ext2_super_block *es,
int wait)
{
ext2_clear_super_error(sb);
spin_lock(&EXT2_SB(sb)->s_lock);
es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
es->s_wtime = cpu_to_le32(get_seconds());
/* unlock before we do IO */
spin_unlock(&EXT2_SB(sb)->s_lock);
mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
if (wait)
sync_dirty_buffer(EXT2_SB(sb)->s_sbh);
Expand All @@ -1151,16 +1165,18 @@ static void ext2_sync_super(struct super_block *sb, struct ext2_super_block *es,
* may have been checked while mounted and e2fsck may have
* set s_state to EXT2_VALID_FS after some corrections.
*/

static int ext2_sync_fs(struct super_block *sb, int wait)
{
struct ext2_sb_info *sbi = EXT2_SB(sb);
struct ext2_super_block *es = EXT2_SB(sb)->s_es;

lock_kernel();
spin_lock(&sbi->s_lock);
if (es->s_state & cpu_to_le16(EXT2_VALID_FS)) {
ext2_debug("setting valid to 0\n");
es->s_state &= cpu_to_le16(~EXT2_VALID_FS);
}
spin_unlock(&sbi->s_lock);
ext2_sync_super(sb, es, wait);
unlock_kernel();

Expand All @@ -1186,6 +1202,7 @@ static int ext2_remount (struct super_block * sb, int * flags, char * data)
int err;

lock_kernel();
spin_lock(&sbi->s_lock);

/* Store the old options */
old_sb_flags = sb->s_flags;
Expand Down Expand Up @@ -1224,12 +1241,14 @@ static int ext2_remount (struct super_block * sb, int * flags, char * data)
sbi->s_mount_opt |= old_mount_opt & EXT2_MOUNT_XIP;
}
if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY)) {
spin_unlock(&sbi->s_lock);
unlock_kernel();
return 0;
}
if (*flags & MS_RDONLY) {
if (le16_to_cpu(es->s_state) & EXT2_VALID_FS ||
!(sbi->s_mount_state & EXT2_VALID_FS)) {
spin_unlock(&sbi->s_lock);
unlock_kernel();
return 0;
}
Expand All @@ -1239,6 +1258,7 @@ static int ext2_remount (struct super_block * sb, int * flags, char * data)
*/
es->s_state = cpu_to_le16(sbi->s_mount_state);
es->s_mtime = cpu_to_le32(get_seconds());
spin_unlock(&sbi->s_lock);
ext2_sync_super(sb, es, 1);
} else {
__le32 ret = EXT2_HAS_RO_COMPAT_FEATURE(sb,
Expand All @@ -1259,6 +1279,7 @@ static int ext2_remount (struct super_block * sb, int * flags, char * data)
sbi->s_mount_state = le16_to_cpu(es->s_state);
if (!ext2_setup_super (sb, es, 0))
sb->s_flags &= ~MS_RDONLY;
spin_unlock(&sbi->s_lock);
ext2_write_super(sb);
}
unlock_kernel();
Expand All @@ -1268,6 +1289,7 @@ static int ext2_remount (struct super_block * sb, int * flags, char * data)
sbi->s_resuid = old_opts.s_resuid;
sbi->s_resgid = old_opts.s_resgid;
sb->s_flags = old_sb_flags;
spin_unlock(&sbi->s_lock);
unlock_kernel();
return err;
}
Expand All @@ -1279,6 +1301,8 @@ static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf)
struct ext2_super_block *es = sbi->s_es;
u64 fsid;

spin_lock(&sbi->s_lock);

if (test_opt (sb, MINIX_DF))
sbi->s_overhead_last = 0;
else if (sbi->s_blocks_last != le32_to_cpu(es->s_blocks_count)) {
Expand Down Expand Up @@ -1333,6 +1357,7 @@ static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf)
le64_to_cpup((void *)es->s_uuid + sizeof(u64));
buf->f_fsid.val[0] = fsid & 0xFFFFFFFFUL;
buf->f_fsid.val[1] = (fsid >> 32) & 0xFFFFFFFFUL;
spin_unlock(&sbi->s_lock);
return 0;
}

Expand Down
2 changes: 2 additions & 0 deletions fs/ext2/xattr.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -345,7 +345,9 @@ static void ext2_xattr_update_super_block(struct super_block *sb)
if (EXT2_HAS_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR))
return;

spin_lock(&EXT2_SB(sb)->s_lock);
EXT2_SET_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR);
spin_unlock(&EXT2_SB(sb)->s_lock);
sb->s_dirt = 1;
mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
}
Expand Down
9 changes: 9 additions & 0 deletions include/linux/ext2_fs_sb.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -106,6 +106,15 @@ struct ext2_sb_info {
spinlock_t s_rsv_window_lock;
struct rb_root s_rsv_window_root;
struct ext2_reserve_window_node s_rsv_window_head;
/*
* s_lock protects against concurrent modifications of s_mount_state,
* s_blocks_last, s_overhead_last and the content of superblock's
* buffer pointed to by sbi->s_es.
*
* Note: It is used in ext2_show_options() to provide a consistent view
* of the mount options.
*/
spinlock_t s_lock;
};

static inline spinlock_t *
Expand Down

0 comments on commit c15271f

Please sign in to comment.