diff options
| -rw-r--r-- | Documentation/filesystems/porting | 10 | ||||
| -rw-r--r-- | fs/read_write.c | 44 | ||||
| -rw-r--r-- | include/linux/fs.h | 4 |
3 files changed, 54 insertions, 4 deletions
diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting index 0eeb3954dea3..6b96773e27cb 100644 --- a/Documentation/filesystems/porting +++ b/Documentation/filesystems/porting @@ -411,3 +411,13 @@ to some pointer to returning that pointer. On errors return ERR_PTR(...). argument; instead of passing IPERM_FLAG_RCU we add MAY_NOT_BLOCK into mask. generic_permission() has also lost the check_acl argument; if you want non-NULL to be used for that inode, put it into ->i_op->check_acl. + +-- +[mandatory] + If you implement your own ->llseek() you must handle SEEK_HOLE and +SEEK_DATA. You can hanle this by returning -EINVAL, but it would be nicer to +support it in some way. The generic handler assumes that the entire file is +data and there is a virtual hole at the end of the file. So if the provided +offset is less than i_size and SEEK_DATA is specified, return the same offset. +If the above is true for the offset and you are given SEEK_HOLE, return the end +of the file. If the offset is i_size or greater return -ENXIO in either case. diff --git a/fs/read_write.c b/fs/read_write.c index 5520f8ad5504..5907b49e4d7e 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -64,6 +64,23 @@ generic_file_llseek_unlocked(struct file *file, loff_t offset, int origin) return file->f_pos; offset += file->f_pos; break; + 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) + return -ENXIO; + break; + case SEEK_HOLE: + /* + * 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) + return -ENXIO; + offset = inode->i_size; + break; } if (offset < 0 && !unsigned_offsets(file)) @@ -128,12 +145,13 @@ EXPORT_SYMBOL(no_llseek); loff_t default_llseek(struct file *file, loff_t offset, int origin) { + struct inode *inode = file->f_path.dentry->d_inode; loff_t retval; - mutex_lock(&file->f_dentry->d_inode->i_mutex); + mutex_lock(&inode->i_mutex); switch (origin) { case SEEK_END: - offset += i_size_read(file->f_path.dentry->d_inode); + offset += i_size_read(inode); break; case SEEK_CUR: if (offset == 0) { @@ -141,6 +159,26 @@ loff_t default_llseek(struct file *file, loff_t offset, int origin) goto out; } offset += file->f_pos; + break; + 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) + return -ENXIO; + break; + case SEEK_HOLE: + /* + * 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) + return -ENXIO; + offset = inode->i_size; + break; } retval = -EINVAL; if (offset >= 0 || unsigned_offsets(file)) { @@ -151,7 +189,7 @@ loff_t default_llseek(struct file *file, loff_t offset, int origin) retval = offset; } out: - mutex_unlock(&file->f_dentry->d_inode->i_mutex); + mutex_unlock(&inode->i_mutex); return retval; } EXPORT_SYMBOL(default_llseek); diff --git a/include/linux/fs.h b/include/linux/fs.h index 824453be9fee..4a61f98823a6 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -32,7 +32,9 @@ #define SEEK_SET 0 /* seek relative to beginning of file */ #define SEEK_CUR 1 /* seek relative to current file position */ #define SEEK_END 2 /* seek relative to end of file */ -#define SEEK_MAX SEEK_END +#define SEEK_DATA 3 /* seek to the next data */ +#define SEEK_HOLE 4 /* seek to the next hole */ +#define SEEK_MAX SEEK_HOLE struct fstrim_range { __u64 start; |