diff options
| author | Al Viro <viro@zeniv.linux.org.uk> | 2010-08-09 12:05:43 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-08-13 13:30:50 -0700 |
| commit | 752638f5e4285a42b2df0394c060054f7154c85e (patch) | |
| tree | 8768767c6472eded20ca5f4d1fb501e6e5a6c074 /include/linux | |
| parent | 252eca4afb1580b80bac2fd19138818e59980873 (diff) | |
Fix sget() race with failing mount
commit 7a4dec53897ecd3367efb1e12fe8a4edc47dc0e9 upstream.
If sget() finds a matching superblock being set up, it'll
grab an active reference to it and grab s_umount. That's
fine - we'll wait for completion of foofs_get_sb() that way.
However, if said foofs_get_sb() fails we'll end up holding
the halfway-created superblock. deactivate_locked_super()
called by foofs_get_sb() will just unlock the sucker since
we are holding another active reference to it.
What we need is a way to tell if superblock has been successfully
set up. Unfortunately, neither ->s_root nor the check for
MS_ACTIVE quite fit. Cheap and easy way, suitable for backport:
new flag set by the (only) caller of ->get_sb(). If that flag
isn't present by the time sget() grabbed s_umount on preexisting
superblock it has found, it's seeing a stillborn and should
just bury it with deactivate_locked_super() (and repeat the search).
Longer term we want to set that flag in ->get_sb() instances (and
check for it to distinguish between "sget() found us a live sb"
and "sget() has allocated an sb, we need to set it up" in there,
instead of checking ->s_root as we do now).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/fs.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/fs.h b/include/linux/fs.h index 68ca1b0491af..3cdaa57862cb 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -209,6 +209,7 @@ struct inodes_stat_t { #define MS_KERNMOUNT (1<<22) /* this is a kern_mount call */ #define MS_I_VERSION (1<<23) /* Update inode I_version field */ #define MS_STRICTATIME (1<<24) /* Always perform atime updates */ +#define MS_BORN (1<<29) #define MS_ACTIVE (1<<30) #define MS_NOUSER (1<<31) |