diff options
| -rw-r--r-- | fs/direct-io.c | 129 | ||||
| -rw-r--r-- | fs/ocfs2/aops.c | 34 | ||||
| -rw-r--r-- | fs/xfs/linux-2.6/xfs_aops.c | 20 | ||||
| -rw-r--r-- | include/linux/fs.h | 22 |
4 files changed, 71 insertions, 134 deletions
diff --git a/fs/direct-io.c b/fs/direct-io.c index 9f34bb9b1ecb..4012885d027f 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -53,13 +53,6 @@ * * If blkfactor is zero then the user's request was aligned to the filesystem's * blocksize. - * - * lock_type is DIO_LOCKING for regular files on direct-IO-naive filesystems. - * This determines whether we need to do the fancy locking which prevents - * direct-IO from being able to read uninitialised disk blocks. If its zero - * (blockdev) this locking is not done, and if it is DIO_OWN_LOCKING i_mutex is - * not held for the entire direct write (taken briefly, initially, during a - * direct read though, but its never held for the duration of a direct-IO). */ struct dio { @@ -68,7 +61,7 @@ struct dio { struct inode *inode; int rw; loff_t i_size; /* i_size when submitted */ - int lock_type; /* doesn't change */ + int flags; /* doesn't change */ unsigned blkbits; /* doesn't change */ unsigned blkfactor; /* When we're using an alignment which is finer than the filesystem's soft @@ -246,7 +239,8 @@ static int dio_complete(struct dio *dio, loff_t offset, int ret) if (dio->end_io && dio->result) dio->end_io(dio->iocb, offset, transferred, dio->map_bh.b_private); - if (dio->lock_type == DIO_LOCKING) + + if (dio->flags & DIO_LOCKING) /* lockdep: non-owner release */ up_read_non_owner(&dio->inode->i_alloc_sem); @@ -521,21 +515,24 @@ static int get_more_blocks(struct dio *dio) map_bh->b_state = 0; map_bh->b_size = fs_count << dio->inode->i_blkbits; + /* + * For writes inside i_size on a DIO_SKIP_HOLES filesystem we + * forbid block creations: only overwrites are permitted. + * We will return early to the caller once we see an + * unmapped buffer head returned, and the caller will fall + * back to buffered I/O. + * + * Otherwise the decision is left to the get_blocks method, + * which may decide to handle it or also return an unmapped + * buffer head. + */ create = dio->rw & WRITE; - if (dio->lock_type == DIO_LOCKING) { + if (dio->flags & DIO_SKIP_HOLES) { if (dio->block_in_file < (i_size_read(dio->inode) >> dio->blkbits)) create = 0; - } else if (dio->lock_type == DIO_NO_LOCKING) { - create = 0; } - /* - * For writes inside i_size we forbid block creations: only - * overwrites are permitted. We fall back to buffered writes - * at a higher level for inside-i_size block-instantiating - * writes. - */ ret = (*dio->get_block)(dio->inode, fs_startblk, map_bh, create); } @@ -1045,7 +1042,7 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode, * we can let i_mutex go now that its achieved its purpose * of protecting us from looking up uninitialized blocks. */ - if ((rw == READ) && (dio->lock_type == DIO_LOCKING)) + if (rw == READ && (dio->flags & DIO_LOCKING)) mutex_unlock(&dio->inode->i_mutex); /* @@ -1092,30 +1089,28 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode, /* * This is a library function for use by filesystem drivers. - * The locking rules are governed by the dio_lock_type parameter. * - * DIO_NO_LOCKING (no locking, for raw block device access) - * For writes, i_mutex is not held on entry; it is never taken. + * The locking rules are governed by the flags parameter: + * - if the flags value contains DIO_LOCKING we use a fancy locking + * scheme for dumb filesystems. + * For writes this function is called under i_mutex and returns with + * i_mutex held, for reads, i_mutex is not held on entry, but it is + * taken and dropped again before returning. + * For reads and writes i_alloc_sem is taken in shared mode and released + * on I/O completion (which may happen asynchronously after returning to + * the caller). * - * DIO_LOCKING (simple locking for regular files) - * For writes we are called under i_mutex and return with i_mutex held, even - * though it is internally dropped. - * For reads, i_mutex is not held on entry, but it is taken and dropped before - * returning. - * - * DIO_OWN_LOCKING (filesystem provides synchronisation and handling of - * uninitialised data, allowing parallel direct readers and writers) - * For writes we are called without i_mutex, return without it, never touch it. - * For reads we are called under i_mutex and return with i_mutex held, even - * though it may be internally dropped. - * - * Additional i_alloc_sem locking requirements described inline below. + * - if the flags value does NOT contain DIO_LOCKING we don't use any + * internal locking but rather rely on the filesystem to synchronize + * direct I/O reads/writes versus each other and truncate. + * For reads and writes both i_mutex and i_alloc_sem are not held on + * entry and are never taken. */ ssize_t __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, struct block_device *bdev, const struct iovec *iov, loff_t offset, unsigned long nr_segs, get_block_t get_block, dio_iodone_t end_io, - int dio_lock_type) + int flags) { int seg; size_t size; @@ -1126,8 +1121,6 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, ssize_t retval = -EINVAL; loff_t end = offset; struct dio *dio; - int release_i_mutex = 0; - int acquire_i_mutex = 0; if (rw & WRITE) rw = WRITE_ODIRECT_PLUG; @@ -1168,43 +1161,30 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, */ memset(dio, 0, offsetof(struct dio, pages)); - /* - * For block device access DIO_NO_LOCKING is used, - * neither readers nor writers do any locking at all - * For regular files using DIO_LOCKING, - * readers need to grab i_mutex and i_alloc_sem - * writers need to grab i_alloc_sem only (i_mutex is already held) - * For regular files using DIO_OWN_LOCKING, - * neither readers nor writers take any locks here - */ - dio->lock_type = dio_lock_type; - if (dio_lock_type != DIO_NO_LOCKING) { + dio->flags = flags; + if (dio->flags & DIO_LOCKING) { /* watch out for a 0 len io from a tricksy fs */ if (rw == READ && end > offset) { - struct address_space *mapping; + struct address_space *mapping = + iocb->ki_filp->f_mapping; - mapping = iocb->ki_filp->f_mapping; - if (dio_lock_type != DIO_OWN_LOCKING) { - mutex_lock(&inode->i_mutex); - release_i_mutex = 1; - } + /* will be released by direct_io_worker */ + mutex_lock(&inode->i_mutex); retval = filemap_write_and_wait_range(mapping, offset, end - 1); if (retval) { + mutex_unlock(&inode->i_mutex); kfree(dio); goto out; } - - if (dio_lock_type == DIO_OWN_LOCKING) { - mutex_unlock(&inode->i_mutex); - acquire_i_mutex = 1; - } } - if (dio_lock_type == DIO_LOCKING) - /* lockdep: not the owner will release it */ - down_read_non_owner(&inode->i_alloc_sem); + /* + * Will be released at I/O completion, possibly in a + * different thread. + */ + down_read_non_owner(&inode->i_alloc_sem); } /* @@ -1222,24 +1202,19 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, /* * In case of error extending write may have instantiated a few * blocks outside i_size. Trim these off again for DIO_LOCKING. - * NOTE: DIO_NO_LOCK/DIO_OWN_LOCK callers have to handle this by - * it's own meaner. + * + * NOTE: filesystems with their own locking have to handle this + * on their own. */ - if (unlikely(retval < 0 && (rw & WRITE))) { - loff_t isize = i_size_read(inode); - - if (end > isize && dio_lock_type == DIO_LOCKING) - vmtruncate(inode, isize); + if (dio->flags & DIO_LOCKING) { + if (unlikely((rw & WRITE) && retval < 0)) { + loff_t isize = i_size_read(inode); + if (end > isize) + vmtruncate(inode, isize); + } } - if (rw == READ && dio_lock_type == DIO_LOCKING) - release_i_mutex = 0; - out: - if (release_i_mutex) - mutex_unlock(&inode->i_mutex); - else if (acquire_i_mutex) - mutex_lock(&inode->i_mutex); return retval; } EXPORT_SYMBOL(__blockdev_direct_IO); diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c index deb2b132ae5e..3dae4a13f6e4 100644 --- a/fs/ocfs2/aops.c +++ b/fs/ocfs2/aops.c @@ -547,6 +547,9 @@ bail: * * called like this: dio->get_blocks(dio->inode, fs_startblk, * fs_count, map_bh, dio->rw == WRITE); + * + * Note that we never bother to allocate blocks here, and thus ignore the + * create argument. */ static int ocfs2_direct_IO_get_blocks(struct inode *inode, sector_t iblock, struct buffer_head *bh_result, int create) @@ -563,14 +566,6 @@ static int ocfs2_direct_IO_get_blocks(struct inode *inode, sector_t iblock, inode_blocks = ocfs2_blocks_for_bytes(inode->i_sb, i_size_read(inode)); - /* - * Any write past EOF is not allowed because we'd be extending. - */ - if (create && (iblock + max_blocks) > inode_blocks) { - ret = -EIO; - goto bail; - } - /* This figures out the size of the next contiguous block, and * our logical offset */ ret = ocfs2_extent_map_get_blocks(inode, iblock, &p_blkno, @@ -582,15 +577,6 @@ static int ocfs2_direct_IO_get_blocks(struct inode *inode, sector_t iblock, goto bail; } - if (!ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)) && !p_blkno && create) { - ocfs2_error(inode->i_sb, - "Inode %llu has a hole at block %llu\n", - (unsigned long long)OCFS2_I(inode)->ip_blkno, - (unsigned long long)iblock); - ret = -EROFS; - goto bail; - } - /* We should already CoW the refcounted extent. */ BUG_ON(ext_flags & OCFS2_EXT_REFCOUNTED); /* @@ -601,20 +587,8 @@ static int ocfs2_direct_IO_get_blocks(struct inode *inode, sector_t iblock, */ if (p_blkno && !(ext_flags & OCFS2_EXT_UNWRITTEN)) map_bh(bh_result, inode->i_sb, p_blkno); - else { - /* - * ocfs2_prepare_inode_for_write() should have caught - * the case where we'd be filling a hole and triggered - * a buffered write instead. - */ - if (create) { - ret = -EIO; - mlog_errno(ret); - goto bail; - } - + else clear_buffer_mapped(bh_result); - } /* make sure we don't map more than max_blocks blocks here as that's all the kernel will handle at this point. */ diff --git a/fs/xfs/linux-2.6/xfs_aops.c b/fs/xfs/linux-2.6/xfs_aops.c index d798c54296eb..66abe36c1213 100644 --- a/fs/xfs/linux-2.6/xfs_aops.c +++ b/fs/xfs/linux-2.6/xfs_aops.c @@ -1474,19 +1474,13 @@ xfs_vm_direct_IO( bdev = xfs_find_bdev_for_inode(XFS_I(inode)); - if (rw == WRITE) { - iocb->private = xfs_alloc_ioend(inode, IOMAP_UNWRITTEN); - ret = blockdev_direct_IO_own_locking(rw, iocb, inode, - bdev, iov, offset, nr_segs, - xfs_get_blocks_direct, - xfs_end_io_direct); - } else { - iocb->private = xfs_alloc_ioend(inode, IOMAP_READ); - ret = blockdev_direct_IO_no_locking(rw, iocb, inode, - bdev, iov, offset, nr_segs, - xfs_get_blocks_direct, - xfs_end_io_direct); - } + iocb->private = xfs_alloc_ioend(inode, rw == WRITE ? + IOMAP_UNWRITTEN : IOMAP_READ); + + ret = blockdev_direct_IO_no_locking(rw, iocb, inode, bdev, iov, + offset, nr_segs, + xfs_get_blocks_direct, + xfs_end_io_direct); if (unlikely(ret != -EIOCBQUEUED && iocb->private)) xfs_destroy_ioend(iocb->private); diff --git a/include/linux/fs.h b/include/linux/fs.h index a057f48eb156..b23a7018eb90 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2264,9 +2264,11 @@ ssize_t __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, int lock_type); enum { - DIO_LOCKING = 1, /* need locking between buffered and direct access */ - DIO_NO_LOCKING, /* bdev; no locking at all between buffered/direct */ - DIO_OWN_LOCKING, /* filesystem locks buffered and direct internally */ + /* need locking between buffered and direct access */ + DIO_LOCKING = 0x01, + + /* filesystem does not support filling holes */ + DIO_SKIP_HOLES = 0x02, }; static inline ssize_t blockdev_direct_IO(int rw, struct kiocb *iocb, @@ -2275,7 +2277,8 @@ static inline ssize_t blockdev_direct_IO(int rw, struct kiocb *iocb, dio_iodone_t end_io) { return __blockdev_direct_IO(rw, iocb, inode, bdev, iov, offset, - nr_segs, get_block, end_io, DIO_LOCKING); + nr_segs, get_block, end_io, + DIO_LOCKING | DIO_SKIP_HOLES); } static inline ssize_t blockdev_direct_IO_no_locking(int rw, struct kiocb *iocb, @@ -2284,16 +2287,7 @@ static inline ssize_t blockdev_direct_IO_no_locking(int rw, struct kiocb *iocb, dio_iodone_t end_io) { return __blockdev_direct_IO(rw, iocb, inode, bdev, iov, offset, - nr_segs, get_block, end_io, DIO_NO_LOCKING); -} - -static inline ssize_t blockdev_direct_IO_own_locking(int rw, struct kiocb *iocb, - struct inode *inode, struct block_device *bdev, const struct iovec *iov, - loff_t offset, unsigned long nr_segs, get_block_t get_block, - dio_iodone_t end_io) -{ - return __blockdev_direct_IO(rw, iocb, inode, bdev, iov, offset, - nr_segs, get_block, end_io, DIO_OWN_LOCKING); + nr_segs, get_block, end_io, 0); } #endif |
