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| author | Al Viro <viro@zeniv.linux.org.uk> | 2025-08-26 13:57:42 -0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2025-09-02 19:35:58 -0400 |
| commit | 5423426a79dd4d4422750b063febed40f362afcc (patch) | |
| tree | 8ce1660de9cdb5bc816f81b3681218d9386cf3d9 | |
| parent | 8281f98a68d3306b2e47e6bb00708525562ccfdf (diff) | |
| download | random-5423426a79dd4d4422750b063febed40f362afcc.tar.gz | |
switch do_new_mount_fc() to fc_mount()
Prior to the call of do_new_mount_fc() the caller has just done successful
vfs_get_tree(). Then do_new_mount_fc() does several checks on resulting
superblock, and either does fc_drop_locked() and returns an error or
proceeds to unlock the superblock and call vfs_create_mount().
The thing is, there's no reason to delay that unlock + vfs_create_mount() -
the tests do not rely upon the state of ->s_umount and
fc_drop_locked()
put_fs_context()
is equivalent to
unlock ->s_umount
put_fs_context()
Doing vfs_create_mount() before the checks allows us to move vfs_get_tree()
from caller to do_new_mount_fc() and collapse it with vfs_create_mount()
into an fc_mount() call.
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| -rw-r--r-- | fs/namespace.c | 29 |
1 files changed, 12 insertions, 17 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index 0474b3a93dbf28..9b575c9eee0bb9 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -3705,25 +3705,20 @@ static bool mount_too_revealing(const struct super_block *sb, int *new_mnt_flags static int do_new_mount_fc(struct fs_context *fc, struct path *mountpoint, unsigned int mnt_flags) { - struct vfsmount *mnt; struct pinned_mountpoint mp = {}; - struct super_block *sb = fc->root->d_sb; + struct super_block *sb; + struct vfsmount *mnt = fc_mount(fc); int error; + if (IS_ERR(mnt)) + return PTR_ERR(mnt); + + sb = fc->root->d_sb; error = security_sb_kern_mount(sb); if (!error && mount_too_revealing(sb, &mnt_flags)) error = -EPERM; - - if (unlikely(error)) { - fc_drop_locked(fc); - return error; - } - - up_write(&sb->s_umount); - - mnt = vfs_create_mount(fc); - if (IS_ERR(mnt)) - return PTR_ERR(mnt); + if (unlikely(error)) + goto out; mnt_warn_timestamp_expiry(mountpoint, mnt); @@ -3731,10 +3726,12 @@ static int do_new_mount_fc(struct fs_context *fc, struct path *mountpoint, if (!error) { error = do_add_mount(real_mount(mnt), mp.mp, mountpoint, mnt_flags); + if (!error) + mnt = NULL; // consumed on success unlock_mount(&mp); } - if (error < 0) - mntput(mnt); +out: + mntput(mnt); return error; } @@ -3789,8 +3786,6 @@ static int do_new_mount(struct path *path, const char *fstype, int sb_flags, if (!err && !mount_capable(fc)) err = -EPERM; if (!err) - err = vfs_get_tree(fc); - if (!err) err = do_new_mount_fc(fc, path, mnt_flags); put_fs_context(fc); |