diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index e4e57d59edb7ca7e6634e1ef251bb142bfaa08b8..1266f6e9cdb22a309d7da8893963fc3765824b65 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1821,7 +1821,7 @@ static loff_t btrfs_file_llseek(struct file *file, loff_t offset, int origin)
switch (origin) {
case SEEK_END:
case SEEK_CUR:
- offset = generic_file_llseek_unlocked(file, offset, origin);
+ offset = generic_file_llseek(file, offset, origin);
goto out;
case SEEK_DATA:
case SEEK_HOLE:
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 54b8f1e7da9465b0f0aad5b245fda0ef7810f84e..db7ce87d37a5919bee6ca27a6d39c20168924f92 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -723,7 +723,7 @@ static loff_t cifs_llseek(struct file *file, loff_t offset, int origin)
if (rc < 0)
return (loff_t)rc;
}
- return generic_file_llseek_unlocked(file, offset, origin);
+ return generic_file_llseek(file, offset, origin);
}
static int cifs_setlease(struct file *file, long arg, struct file_lock **lease)
diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index edeb9e80290382b39491d67c40ed3802535aac2b..fe6bc0207818ab80c9aa3d8f490e06d45ea006ad 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -63,11 +63,11 @@ static loff_t gfs2_llseek(struct file *file, loff_t offset, int origin)
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 --git a/fs/nfs/file.c b/fs/nfs/file.c
index 28b8c3f3cda3af002e99044fee907f119ac78afb..12623abcf3d4c8e5dc24999265aa3878ebf3a1ba 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -198,11 +198,12 @@ static loff_t nfs_file_llseek(struct file *filp, loff_t offset, int origin)
if (retval < 0)
return (loff_t)retval;
+ /* AK: should drop this lock. Unlikely to be needed. */
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 --git a/fs/read_write.c b/fs/read_write.c
index 179f1c33ea578481cdc3388d54717089704a51a3..672b187def6296a1de19bba537047a1e1010f9ae 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -35,23 +35,45 @@ static inline int unsigned_offsets(struct file *file)
return file->f_mode & FMODE_UNSIGNED_OFFSET;
}
+static loff_t lseek_execute(struct file *file, struct inode *inode,
+ loff_t offset, loff_t maxsize)
+{
+ if (offset < 0 && !unsigned_offsets(file))
+ return -EINVAL;
+ if (offset > maxsize)
+ return -EINVAL;
+
+ if (offset != file->f_pos) {
+ file->f_pos = offset;
+ file->f_version = 0;
+ }
+ return offset;
+}
+
/**
- * 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 usable for all normal local
+ * filesystems. It just updates the file offset to the value specified by
+ * @offset and @origin under i_mutex.
+ *
+ * Synchronization:
+ * SEEK_SET is unsynchronized (but atomic on 64bit platforms)
+ * SEEK_CUR is synchronized against other SEEK_CURs, but not read/writes.
+ * read/writes behave like SEEK_SET against seeks.
+ * SEEK_END
*/
loff_t
-generic_file_llseek_unlocked(struct file *file, loff_t offset, int origin)
+generic_file_llseek(struct file *file, loff_t offset, int origin)
{
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:
/*
@@ -62,14 +84,22 @@ generic_file_llseek_unlocked(struct file *file, loff_t offset, int origin)
*/
if (offset == 0)
return file->f_pos;
- offset += file->f_pos;
- break;
+ /*
+ * f_lock protects against read/modify/write race with other
+ * SEEK_CURs. Note that parallel writes and reads behave
+ * like SEEK_SET.
+ */
+ spin_lock(&file->f_lock);
+ offset = lseek_execute(file, inode, file->f_pos + offset,
+ inode->i_sb->s_maxbytes);
+ spin_unlock(&file->f_lock);
+ return offset;
case SEEK_DATA:
/*
* In the generic case the entire file is data, so as long as
* offset isn't at the end of the file then the offset is data.
*/
- if (offset >= inode->i_size)
+ if (offset >= i_size_read(inode))
return -ENXIO;
break;
case SEEK_HOLE:
@@ -77,46 +107,13 @@ generic_file_llseek_unlocked(struct file *file, loff_t offset, int origin)
* There is a virtual hole at the end of the file, so as long as
* offset isn't i_size or larger, return i_size.
*/
- if (offset >= inode->i_size)
+ if (offset >= i_size_read(inode))
return -ENXIO;
- offset = inode->i_size;
+ offset = i_size_read(inode);
break;
}
- if (offset < 0 && !unsigned_offsets(file))
- return -EINVAL;
- if (offset > inode->i_sb->s_maxbytes)
- return -EINVAL;
-
- /* Special lock needed here? */
- if (offset != file->f_pos) {
- 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);
-
- return rval;
+ return lseek_execute(file, inode, offset, inode->i_sb->s_maxbytes);
}
EXPORT_SYMBOL(generic_file_llseek);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index c1884e974ff4bfd65e6d56df46c5736a3944fdc4..db85196f63088d878645db104c3e1fc172a746eb 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -964,7 +964,12 @@ struct file {
#define f_dentry f_path.dentry
#define f_vfsmnt f_path.mnt
const struct file_operations *f_op;
- spinlock_t f_lock; /* f_ep_links, f_flags, no IRQ */
+
+ /*
+ * Protects f_ep_links, f_flags, f_pos vs i_size in lseek SEEK_CUR.
+ * Must not be taken from IRQ context.
+ */
+ spinlock_t f_lock;
#ifdef CONFIG_SMP
int f_sb_list_cpu;
#endif
@@ -2398,8 +2403,6 @@ file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping);
extern loff_t noop_llseek(struct file *file, loff_t offset, int origin);
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);