[RESEND] [PATCH] lseek: remove i_mutex
From: Hisashi Hifumi
Date: Wed Feb 04 2009 - 21:28:26 EST
Hi
I removed i_mutex from generic_file_llseek.
I think that the reason of protecting lseek with i_mutex is just
touching i_size atomically.
So I introduce i_size_read here so i_mutex is no longer needed.
Following patch removes i_mutex from generic_file_llseek, and deletes
generic_file_llseek_nolock totally.
Currently there is i_mutex contention not only around lseek, but also fsync or write.
So, I think we can mitigate i_mutex contention between fsync lseek and write by
removing i_mutex.
Thanks.
Signed-off-by: Hisashi Hifumi <hifumi.hisashi@xxxxxxxxxxxxx>
diff -Nrup linux-2.6.29-rc3.org/fs/cifs/cifsfs.c linux-2.6.29-rc3.lseek/fs/cifs/cifsfs.c
--- linux-2.6.29-rc3.org/fs/cifs/cifsfs.c 2009-02-02 16:53:19.000000000 +0900
+++ linux-2.6.29-rc3.lseek/fs/cifs/cifsfs.c 2009-02-02 20:25:33.000000000 +0900
@@ -636,7 +636,7 @@ static loff_t cifs_llseek(struct file *f
if (retval < 0)
return (loff_t)retval;
}
- return generic_file_llseek_unlocked(file, offset, origin);
+ return generic_file_llseek(file, offset, origin);
}
#ifdef CONFIG_CIFS_EXPERIMENTAL
diff -Nrup linux-2.6.29-rc3.org/fs/gfs2/ops_file.c linux-2.6.29-rc3.lseek/fs/gfs2/ops_file.c
--- linux-2.6.29-rc3.org/fs/gfs2/ops_file.c 2009-02-02 16:53:19.000000000 +0900
+++ linux-2.6.29-rc3.lseek/fs/gfs2/ops_file.c 2009-02-02 20:25:33.000000000 +0900
@@ -62,11 +62,11 @@ static loff_t gfs2_llseek(struct file *f
error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY,
&i_gh);
if (!error) {
- error = generic_file_llseek_unlocked(file, offset, origin);
+ error = generic_file_llseek(file, offset, origin);
gfs2_glock_dq_uninit(&i_gh);
}
} else
- error = generic_file_llseek_unlocked(file, offset, origin);
+ error = generic_file_llseek(file, offset, origin);
return error;
}
diff -Nrup linux-2.6.29-rc3.org/fs/ncpfs/file.c linux-2.6.29-rc3.lseek/fs/ncpfs/file.c
--- linux-2.6.29-rc3.org/fs/ncpfs/file.c 2008-12-25 08:26:37.000000000 +0900
+++ linux-2.6.29-rc3.lseek/fs/ncpfs/file.c 2009-02-02 20:25:33.000000000 +0900
@@ -286,7 +286,7 @@ static loff_t ncp_remote_llseek(struct f
{
loff_t ret;
lock_kernel();
- ret = generic_file_llseek_unlocked(file, offset, origin);
+ ret = generic_file_llseek(file, offset, origin);
unlock_kernel();
return ret;
}
diff -Nrup linux-2.6.29-rc3.org/fs/nfs/file.c linux-2.6.29-rc3.lseek/fs/nfs/file.c
--- linux-2.6.29-rc3.org/fs/nfs/file.c 2009-02-02 16:53:19.000000000 +0900
+++ linux-2.6.29-rc3.lseek/fs/nfs/file.c 2009-02-02 20:25:33.000000000 +0900
@@ -194,10 +194,10 @@ static loff_t nfs_file_llseek(struct fil
return (loff_t)retval;
spin_lock(&inode->i_lock);
- loff = generic_file_llseek_unlocked(filp, offset, origin);
+ loff = generic_file_llseek(filp, offset, origin);
spin_unlock(&inode->i_lock);
} else
- loff = generic_file_llseek_unlocked(filp, offset, origin);
+ loff = generic_file_llseek(filp, offset, origin);
return loff;
}
diff -Nrup linux-2.6.29-rc3.org/fs/read_write.c linux-2.6.29-rc3.lseek/fs/read_write.c
--- linux-2.6.29-rc3.org/fs/read_write.c 2009-02-02 16:53:19.000000000 +0900
+++ linux-2.6.29-rc3.lseek/fs/read_write.c 2009-02-02 20:25:33.000000000 +0900
@@ -32,22 +32,23 @@ const struct file_operations generic_ro_
EXPORT_SYMBOL(generic_ro_fops);
/**
- * generic_file_llseek_unlocked - lockless generic llseek implementation
+ * generic_file_llseek - generic llseek implementation for regular files
* @file: file structure to seek on
* @offset: file offset to seek to
* @origin: type of seek
*
- * Updates the file offset to the value specified by @offset and @origin.
- * Locking must be provided by the caller.
+ * This is a generic implemenation of ->llseek useable for all normal local
+ * filesystems. It just updates the file offset to the value specified by
+ * @offset and @origin.
*/
-loff_t
-generic_file_llseek_unlocked(struct file *file, loff_t offset, int origin)
+loff_t generic_file_llseek(struct file *file, loff_t offset, int origin)
{
+ loff_t rval;
struct inode *inode = file->f_mapping->host;
switch (origin) {
case SEEK_END:
- offset += inode->i_size;
+ offset += i_size_read(inode);
break;
case SEEK_CUR:
/*
@@ -70,28 +71,7 @@ generic_file_llseek_unlocked(struct file
file->f_pos = offset;
file->f_version = 0;
}
-
- return offset;
-}
-EXPORT_SYMBOL(generic_file_llseek_unlocked);
-
-/**
- * generic_file_llseek - generic llseek implementation for regular files
- * @file: file structure to seek on
- * @offset: file offset to seek to
- * @origin: type of seek
- *
- * This is a generic implemenation of ->llseek useable for all normal local
- * filesystems. It just updates the file offset to the value specified by
- * @offset and @origin under i_mutex.
- */
-loff_t generic_file_llseek(struct file *file, loff_t offset, int origin)
-{
- loff_t rval;
-
- mutex_lock(&file->f_dentry->d_inode->i_mutex);
- rval = generic_file_llseek_unlocked(file, offset, origin);
- mutex_unlock(&file->f_dentry->d_inode->i_mutex);
+ rval = offset;
return rval;
}
diff -Nrup linux-2.6.29-rc3.org/fs/smbfs/file.c linux-2.6.29-rc3.lseek/fs/smbfs/file.c
--- linux-2.6.29-rc3.org/fs/smbfs/file.c 2009-02-02 16:53:19.000000000 +0900
+++ linux-2.6.29-rc3.lseek/fs/smbfs/file.c 2009-02-02 20:25:33.000000000 +0900
@@ -426,7 +426,7 @@ static loff_t smb_remote_llseek(struct f
{
loff_t ret;
lock_kernel();
- ret = generic_file_llseek_unlocked(file, offset, origin);
+ ret = generic_file_llseek(file, offset, origin);
unlock_kernel();
return ret;
}
diff -Nrup linux-2.6.29-rc3.org/include/linux/fs.h linux-2.6.29-rc3.lseek/include/linux/fs.h
--- linux-2.6.29-rc3.org/include/linux/fs.h 2009-02-02 16:53:21.000000000 +0900
+++ linux-2.6.29-rc3.lseek/include/linux/fs.h 2009-02-02 20:25:33.000000000 +0900
@@ -1982,8 +1982,6 @@ extern void
file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping);
extern loff_t no_llseek(struct file *file, loff_t offset, int origin);
extern loff_t generic_file_llseek(struct file *file, loff_t offset, int origin);
-extern loff_t generic_file_llseek_unlocked(struct file *file, loff_t offset,
- int origin);
extern int generic_file_open(struct inode * inode, struct file * filp);
extern int nonseekable_open(struct inode * inode, struct file * filp);
--
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