diff options
| -rw-r--r-- | fs/btrfs/file.c | 2 | ||||
| -rw-r--r-- | fs/cifs/cifsfs.c | 2 | ||||
| -rw-r--r-- | fs/gfs2/file.c | 4 | ||||
| -rw-r--r-- | fs/nfs/file.c | 5 | ||||
| -rw-r--r-- | fs/read_write.c | 85 | ||||
| -rw-r--r-- | include/linux/fs.h | 9 |
6 files changed, 54 insertions, 53 deletions
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index e4e57d5..1266f6e 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 54b8f1e..db7ce87 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 edeb9e8..fe6bc02 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 28b8c3f..12623ab 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 179f1c3..672b187 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 c1884e9..db85196 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); |
