From 724bb09fdc06d4ff03757b25d6dba9ef1b133e8f Mon Sep 17 00:00:00 2001 From: Al Viro Date: Wed, 17 Jun 2015 12:02:56 -0400 Subject: ufs: don't use lock_ufs() for block pointers tree protection * stores to block pointers are under per-inode seqlock (meta_lock) and mutex (truncate_mutex) * fetches of block pointers are either under truncate_mutex, or wrapped into seqretry loop on meta_lock * all changes of ->i_size are under truncate_mutex and i_mutex * all changes of ->i_lastfrag are under truncate_mutex It's similar to what ext2 is doing; the main difference is that unlike ext2 we can't rely upon the atomicity of stores into block pointers - on UFS2 they are 64bit. So we can't cut the corner when switching a pointer from NULL to non-NULL as we could in ext2_splice_branch() and need to use meta_lock on all modifications. We use seqlock where ext2 uses rwlock; ext2 could probably also benefit from such change... Another non-trivial difference is that with UFS we *cannot* have reader grab truncate_mutex in case of race - it has to keep retrying. That might be possible to change, but not until we lift tail unpacking several levels up in call chain. After that commit we do *NOT* hold fs-wide serialization on accesses to block pointers anymore. Moreover, lock_ufs() can become a normal mutex now - it's only used on statfs, remount and sync_fs and none of those uses are recursive. As the matter of fact, *now* it can be collapsed with ->s_lock, and be eventually replaced with saner per-cylinder-group spinlocks, but that's a separate story. Signed-off-by: Al Viro --- fs/ufs/super.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'fs/ufs/super.c') diff --git a/fs/ufs/super.c b/fs/ufs/super.c index 250579a80d90..15cd3338340c 100644 --- a/fs/ufs/super.c +++ b/fs/ufs/super.c @@ -1429,6 +1429,8 @@ static struct inode *ufs_alloc_inode(struct super_block *sb) return NULL; ei->vfs_inode.i_version = 1; + seqlock_init(&ei->meta_lock); + mutex_init(&ei->truncate_mutex); return &ei->vfs_inode; } -- cgit v1.2.3-70-g09d2 From dff7cfd36e305488421d82a0ed3dd0209c333745 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Tue, 16 Jun 2015 04:27:05 -0400 Subject: ufs: kill lock_ufs() There were 3 remaining users; in two of them we took ->s_lock immediately after lock_ufs() and held it until just before unlock_ufs(); the third one (statfs) could not be called from itself or from other two (remount and sync_fs). Just use ->s_lock in statfs and don't bother with lock_ufs at all. Signed-off-by: Al Viro --- fs/ufs/super.c | 34 ++-------------------------------- fs/ufs/ufs.h | 5 ----- 2 files changed, 2 insertions(+), 37 deletions(-) (limited to 'fs/ufs/super.c') diff --git a/fs/ufs/super.c b/fs/ufs/super.c index 15cd3338340c..f6390eec02ca 100644 --- a/fs/ufs/super.c +++ b/fs/ufs/super.c @@ -94,22 +94,6 @@ #include "swab.h" #include "util.h" -void lock_ufs(struct super_block *sb) -{ - struct ufs_sb_info *sbi = UFS_SB(sb); - - mutex_lock(&sbi->mutex); - sbi->mutex_owner = current; -} - -void unlock_ufs(struct super_block *sb) -{ - struct ufs_sb_info *sbi = UFS_SB(sb); - - sbi->mutex_owner = NULL; - mutex_unlock(&sbi->mutex); -} - static struct inode *ufs_nfs_get_inode(struct super_block *sb, u64 ino, u32 generation) { struct ufs_sb_private_info *uspi = UFS_SB(sb)->s_uspi; @@ -694,7 +678,6 @@ static int ufs_sync_fs(struct super_block *sb, int wait) struct ufs_super_block_third * usb3; unsigned flags; - lock_ufs(sb); mutex_lock(&UFS_SB(sb)->s_lock); UFSD("ENTER\n"); @@ -714,7 +697,6 @@ static int ufs_sync_fs(struct super_block *sb, int wait) UFSD("EXIT\n"); mutex_unlock(&UFS_SB(sb)->s_lock); - unlock_ufs(sb); return 0; } @@ -758,7 +740,6 @@ static void ufs_put_super(struct super_block *sb) ubh_brelse_uspi (sbi->s_uspi); kfree (sbi->s_uspi); - mutex_destroy(&sbi->mutex); kfree (sbi); sb->s_fs_info = NULL; UFSD("EXIT\n"); @@ -801,7 +782,6 @@ static int ufs_fill_super(struct super_block *sb, void *data, int silent) UFSD("flag %u\n", (int)(sb->s_flags & MS_RDONLY)); - mutex_init(&sbi->mutex); mutex_init(&sbi->s_lock); spin_lock_init(&sbi->work_lock); INIT_DELAYED_WORK(&sbi->sync_work, delayed_sync_fs); @@ -1257,7 +1237,6 @@ magic_found: return 0; failed: - mutex_destroy(&sbi->mutex); if (ubh) ubh_brelse_uspi (uspi); kfree (uspi); @@ -1280,7 +1259,6 @@ static int ufs_remount (struct super_block *sb, int *mount_flags, char *data) unsigned flags; sync_filesystem(sb); - lock_ufs(sb); mutex_lock(&UFS_SB(sb)->s_lock); uspi = UFS_SB(sb)->s_uspi; flags = UFS_SB(sb)->s_flags; @@ -1296,7 +1274,6 @@ static int ufs_remount (struct super_block *sb, int *mount_flags, char *data) ufs_set_opt (new_mount_opt, ONERROR_LOCK); if (!ufs_parse_options (data, &new_mount_opt)) { mutex_unlock(&UFS_SB(sb)->s_lock); - unlock_ufs(sb); return -EINVAL; } if (!(new_mount_opt & UFS_MOUNT_UFSTYPE)) { @@ -1304,14 +1281,12 @@ static int ufs_remount (struct super_block *sb, int *mount_flags, char *data) } else if ((new_mount_opt & UFS_MOUNT_UFSTYPE) != ufstype) { pr_err("ufstype can't be changed during remount\n"); mutex_unlock(&UFS_SB(sb)->s_lock); - unlock_ufs(sb); return -EINVAL; } if ((*mount_flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY)) { UFS_SB(sb)->s_mount_opt = new_mount_opt; mutex_unlock(&UFS_SB(sb)->s_lock); - unlock_ufs(sb); return 0; } @@ -1335,7 +1310,6 @@ static int ufs_remount (struct super_block *sb, int *mount_flags, char *data) #ifndef CONFIG_UFS_FS_WRITE pr_err("ufs was compiled with read-only support, can't be mounted as read-write\n"); mutex_unlock(&UFS_SB(sb)->s_lock); - unlock_ufs(sb); return -EINVAL; #else if (ufstype != UFS_MOUNT_UFSTYPE_SUN && @@ -1345,13 +1319,11 @@ static int ufs_remount (struct super_block *sb, int *mount_flags, char *data) ufstype != UFS_MOUNT_UFSTYPE_UFS2) { pr_err("this ufstype is read-only supported\n"); mutex_unlock(&UFS_SB(sb)->s_lock); - unlock_ufs(sb); return -EINVAL; } if (!ufs_read_cylinder_structures(sb)) { pr_err("failed during remounting\n"); mutex_unlock(&UFS_SB(sb)->s_lock); - unlock_ufs(sb); return -EPERM; } sb->s_flags &= ~MS_RDONLY; @@ -1359,7 +1331,6 @@ static int ufs_remount (struct super_block *sb, int *mount_flags, char *data) } UFS_SB(sb)->s_mount_opt = new_mount_opt; mutex_unlock(&UFS_SB(sb)->s_lock); - unlock_ufs(sb); return 0; } @@ -1391,8 +1362,7 @@ static int ufs_statfs(struct dentry *dentry, struct kstatfs *buf) struct ufs_super_block_third *usb3; u64 id = huge_encode_dev(sb->s_bdev->bd_dev); - lock_ufs(sb); - + mutex_lock(&UFS_SB(sb)->s_lock); usb3 = ubh_get_usb_third(uspi); if ((flags & UFS_TYPE_MASK) == UFS_TYPE_UFS2) { @@ -1413,7 +1383,7 @@ static int ufs_statfs(struct dentry *dentry, struct kstatfs *buf) buf->f_fsid.val[0] = (u32)id; buf->f_fsid.val[1] = (u32)(id >> 32); - unlock_ufs(sb); + mutex_unlock(&UFS_SB(sb)->s_lock); return 0; } diff --git a/fs/ufs/ufs.h b/fs/ufs/ufs.h index ea28b73a8b74..478f35b493a6 100644 --- a/fs/ufs/ufs.h +++ b/fs/ufs/ufs.h @@ -24,8 +24,6 @@ struct ufs_sb_info { unsigned s_cgno[UFS_MAX_GROUP_LOADED]; unsigned short s_cg_loaded; unsigned s_mount_opt; - struct mutex mutex; - struct task_struct *mutex_owner; struct super_block *sb; int work_queued; /* non-zero if the delayed work is queued */ struct delayed_work sync_work; /* FS sync delayed work */ @@ -172,7 +170,4 @@ static inline u32 ufs_dtogd(struct ufs_sb_private_info * uspi, u64 b) return do_div(b, uspi->s_fpg); } -extern void lock_ufs(struct super_block *sb); -extern void unlock_ufs(struct super_block *sb); - #endif /* _UFS_UFS_H */ -- cgit v1.2.3-70-g09d2