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| author | Yongqiang Yang <xiaoqiangnk@gmail.com> | 2011-07-27 05:35:44 +0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2011-07-27 05:35:44 +0400 |
| commit | 8f82f840ec6ab873f520364d443ff6fa1b3f8e22 (patch) | |
| tree | 72d90cdc8f7311ef913b7471e53f718bebbf7414 /fs/ext4/ioctl.c | |
| parent | 2d859db3e4a82a365572592d57624a5f996ed0ec (diff) | |
| download | linux-8f82f840ec6ab873f520364d443ff6fa1b3f8e22.tar.xz | |
ext4: prevent parallel resizers by atomic bit ops
Before this patch, parallel resizers are allowed and protected by a
mutex lock, actually, there is no need to support parallel resizer, so
this patch prevents parallel resizers by atmoic bit ops, like
lock_page() and unlock_page() do.
To do this, the patch removed the mutex lock s_resize_lock from struct
ext4_sb_info and added a unsigned long field named s_resize_flags
which inidicates if there is a resizer.
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Diffstat (limited to 'fs/ext4/ioctl.c')
| -rw-r--r-- | fs/ext4/ioctl.c | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c index 808c554e773f..f18bfe37aff8 100644 --- a/fs/ext4/ioctl.c +++ b/fs/ext4/ioctl.c @@ -202,8 +202,9 @@ setversion_out: struct super_block *sb = inode->i_sb; int err, err2=0; - if (!capable(CAP_SYS_RESOURCE)) - return -EPERM; + err = ext4_resize_begin(sb); + if (err) + return err; if (get_user(n_blocks_count, (__u32 __user *)arg)) return -EFAULT; @@ -221,6 +222,7 @@ setversion_out: if (err == 0) err = err2; mnt_drop_write(filp->f_path.mnt); + ext4_resize_end(sb); return err; } @@ -271,8 +273,9 @@ mext_out: struct super_block *sb = inode->i_sb; int err, err2=0; - if (!capable(CAP_SYS_RESOURCE)) - return -EPERM; + err = ext4_resize_begin(sb); + if (err) + return err; if (copy_from_user(&input, (struct ext4_new_group_input __user *)arg, sizeof(input))) @@ -291,6 +294,7 @@ mext_out: if (err == 0) err = err2; mnt_drop_write(filp->f_path.mnt); + ext4_resize_end(sb); return err; } |