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Subject[PATCH] sysfs: use ilookup5() instead of ilookup5_nowait()
As inode creation is protected by sysfs_mutex, ilookup5_nowait()
always either fails to find at all or finds one which is fully
initialized, so using ilookup5_nowait() or ilookup5() doesn't make any
difference. Switch to ilookup5() as it's planned to be removed. This
change also makes lookup return value handling a bit simpler.

This change was suggested by Al Viro.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Al Viro <viro@hera.kernel.org>
---
Greg, can you please put this for 2.6.28? This should be safe but
this isn't a bug fix and it's way too late for 2.6.27. Thanks.

fs/sysfs/dir.c | 17 ++++++++---------
1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index aedaeba..c04935c 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -370,17 +370,17 @@ void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,
memset(acxt, 0, sizeof(*acxt));
acxt->parent_sd = parent_sd;

- /* Lookup parent inode. inode initialization and I_NEW
- * clearing are protected by sysfs_mutex. By grabbing it and
- * looking up with _nowait variant, inode state can be
- * determined reliably.
+ /* Lookup parent inode. inode initialization is protected by
+ * sysfs_mutex, so inode existence can be determined by
+ * looking up inode while holding sysfs_mutex.
*/
mutex_lock(&sysfs_mutex);

- inode = ilookup5_nowait(sysfs_sb, parent_sd->s_ino, sysfs_ilookup_test,
- parent_sd);
+ inode = ilookup5(sysfs_sb, parent_sd->s_ino, sysfs_ilookup_test,
+ parent_sd);
+ if (inode) {
+ WARN_ON(inode->i_state & I_NEW);

- if (inode && !(inode->i_state & I_NEW)) {
/* parent inode available */
acxt->parent_inode = inode;

@@ -393,8 +393,7 @@ void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,
mutex_lock(&inode->i_mutex);
mutex_lock(&sysfs_mutex);
}
- } else
- iput(inode);
+ }
}

/**

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