[PATCH 19/20] ext2: Add ext2_sb_info s_lock spinlock

Jan Blunck
2009-11-18T09:26:44Z

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

Signed-off-by: Jan Blunck <jblunck@suse.de>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Jan Kara <jack@suse.cz>
---
fs/ext2/inode.c | 2 ++
fs/ext2/super.c | 42 +++++++++++++++++++++++++++++++++++++-----
include/linux/ext2_fs_sb.h | 6 ++++++
3 files changed, 45 insertions(+), 5 deletions(-)

diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index ade6340..65a0d4b 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -1401,9 +1401,11 @@ 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);
}
diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index 5af1775..0ca42fe 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -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(&EXT2_SB(sb)->s_lock);
ext2_sync_super(sb, es);
}

@@ -84,6 +86,9 @@ void ext2_warning (struct super_block * sb, const char * function,
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;
@@ -117,14 +122,16 @@ static void ext2_put_super (struct super_block * sb)

lock_kernel();

- if (sb->s_dirt)
- ext2_write_super(sb);
+ if (sb->s_dirt && !(sb->s_flags & MS_RDONLY))
+ ext2_sync_fs(sb, 1);

ext2_xattr_put_super(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(&EXT2_SB(sb)->s_lock);
ext2_sync_super(sb, es);
}
db_count = sbi->s_gdb_count;
@@ -207,6 +214,7 @@ 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)
@@ -279,6 +287,7 @@ 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;
}

@@ -762,6 +771,12 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
sbi->s_sb_block = sb_block;

/*
+ * mutex for protection of modifications of the superblock while being
+ * write out by ext2_write_super() or ext2_sync_fs().
+ */
+ 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
* is smaller than the default) use the default.
@@ -1103,11 +1118,15 @@ static void ext2_commit_super (struct super_block * sb,
sb->s_dirt = 0;
}

-static void ext2_sync_super(struct super_block *sb, struct ext2_super_block *es)
+static void ext2_sync_super(struct super_block *sb,
+ struct ext2_super_block *es)
{
+ 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);
sync_dirty_buffer(EXT2_SB(sb)->s_sbh);
sb->s_dirt = 0;
@@ -1122,13 +1141,16 @@ static void ext2_sync_super(struct super_block *sb, struct ext2_super_block *es)
* flags to 0. We need to set this flag to 0 since the fs
* may have been checked while mounted and e2fsck may have
* set s_state to EXT2_VALID_FS after some corrections.
+ *
+ * This must be called with sbi->s_lock held.
*/
-
static int ext2_sync_fs(struct super_block *sb, int wait)
{
- struct ext2_super_block *es = EXT2_SB(sb)->s_es;
+ struct ext2_sb_info *sbi = EXT2_SB(sb);
+ struct ext2_super_block *es = sbi->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);
@@ -1137,9 +1159,11 @@ static int ext2_sync_fs(struct super_block *sb, int wait)
es->s_free_inodes_count =
cpu_to_le32(ext2_count_free_inodes(sb));
es->s_mtime = cpu_to_le32(get_seconds());
+ spin_unlock(&EXT2_SB(sb)->s_lock);
ext2_sync_super(sb, es);
} else {
ext2_commit_super(sb, es);
+ spin_unlock(&sbi->s_lock);
}
sb->s_dirt = 0;
unlock_kernel();
@@ -1166,6 +1190,7 @@ 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;
@@ -1203,12 +1228,14 @@ 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;
}
@@ -1237,6 +1264,7 @@ static int ext2_remount (struct super_block * sb, int * flags, char * data)
if (!ext2_setup_super (sb, es, 0))
sb->s_flags &= ~MS_RDONLY;
}
+ spin_unlock(&EXT2_SB(sb)->s_lock);
ext2_sync_super(sb, es);
unlock_kernel();
return 0;
@@ -1245,6 +1273,7 @@ restore_opts:
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;
}
@@ -1256,6 +1285,8 @@ 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)) {
@@ -1310,6 +1341,7 @@ 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;
}

diff --git a/include/linux/ext2_fs_sb.h b/include/linux/ext2_fs_sb.h
index 1cdb663..dbc5934 100644
--- a/include/linux/ext2_fs_sb.h
+++ b/include/linux/ext2_fs_sb.h
@@ -106,6 +106,12 @@ 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;
+ /*
+ * 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.
+ */
+ spinlock_t s_lock;
};

static inline spinlock_t *
--
1.6.4.2