ocfs2: teach ocfs2_file_aio_write() about sparse files
Unfortunately, ocfs2 can no longer make use of generic_file_aio_write_nlock()
because allocating writes will require zeroing of pages adjacent to the I/O
for cluster sizes greater than page size.
Implement a custom file write here, which can order page locks for zeroing.
This also has the advantage that cluster locks can easily be ordered outside
of the page locks.
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 3bcf362..667e5a8 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -33,6 +33,7 @@
#include <linux/sched.h>
#include <linux/pipe_fs_i.h>
#include <linux/mount.h>
+#include <linux/writeback.h>
#define MLOG_MASK_PREFIX ML_INODE
#include <cluster/masklog.h>
@@ -485,13 +486,13 @@
* accessed, and lock them, reserving the appropriate number of bits.
*
* Called from ocfs2_extend_allocation() for file systems which don't
- * support holes, and from ocfs2_prepare_write() for file systems
- * which understand sparse inodes.
+ * support holes, and from ocfs2_write() for file systems which
+ * understand sparse inodes.
*/
-static int ocfs2_lock_allocators(struct inode *inode, struct ocfs2_dinode *di,
- u32 clusters_to_add,
- struct ocfs2_alloc_context **data_ac,
- struct ocfs2_alloc_context **meta_ac)
+int ocfs2_lock_allocators(struct inode *inode, struct ocfs2_dinode *di,
+ u32 clusters_to_add,
+ struct ocfs2_alloc_context **data_ac,
+ struct ocfs2_alloc_context **meta_ac)
{
int ret, num_free_extents;
struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
@@ -518,7 +519,7 @@
* a cluster lock (because we ran out of room for another
* extent) will violate ordering rules.
*
- * Most of the time we'll only be seeing this 1 page at a time
+ * Most of the time we'll only be seeing this 1 cluster at a time
* anyway.
*/
if (!num_free_extents ||
@@ -596,13 +597,6 @@
restart_all:
BUG_ON(le32_to_cpu(fe->i_clusters) != OCFS2_I(inode)->ip_clusters);
- status = ocfs2_lock_allocators(inode, fe, clusters_to_add, &data_ac,
- &meta_ac);
- if (status) {
- mlog_errno(status);
- goto leave;
- }
-
/* blocks peope in read/write from reading our allocation
* until we're done changing it. We depend on i_mutex to block
* other extend/truncate calls while we're here. Ordering wrt
@@ -610,6 +604,13 @@
down_write(&OCFS2_I(inode)->ip_alloc_sem);
drop_alloc_sem = 1;
+ status = ocfs2_lock_allocators(inode, fe, clusters_to_add, &data_ac,
+ &meta_ac);
+ if (status) {
+ mlog_errno(status);
+ goto leave;
+ }
+
credits = ocfs2_calc_extend_credits(osb->sb, fe, clusters_to_add);
handle = ocfs2_start_trans(osb, credits);
if (IS_ERR(handle)) {
@@ -1088,10 +1089,49 @@
return ret;
}
+/*
+ * Will look for holes and unwritten extents in the range starting at
+ * pos for count bytes (inclusive).
+ */
+static int ocfs2_check_range_for_holes(struct inode *inode, loff_t pos,
+ size_t count)
+{
+ int ret = 0;
+ unsigned int extent_flags;
+ u32 cpos, clusters, extent_len, phys_cpos;
+ struct super_block *sb = inode->i_sb;
+
+ cpos = pos >> OCFS2_SB(sb)->s_clustersize_bits;
+ clusters = ocfs2_clusters_for_bytes(sb, pos + count) - cpos;
+
+ while (clusters) {
+ ret = ocfs2_get_clusters(inode, cpos, &phys_cpos, &extent_len,
+ &extent_flags);
+ if (ret < 0) {
+ mlog_errno(ret);
+ goto out;
+ }
+
+ if (phys_cpos == 0 || (extent_flags & OCFS2_EXT_UNWRITTEN)) {
+ ret = 1;
+ break;
+ }
+
+ if (extent_len > clusters)
+ extent_len = clusters;
+
+ clusters -= extent_len;
+ cpos += extent_len;
+ }
+out:
+ return ret;
+}
+
static int ocfs2_prepare_inode_for_write(struct dentry *dentry,
loff_t *ppos,
size_t count,
- int appending)
+ int appending,
+ int *direct_io)
{
int ret = 0, meta_level = appending;
struct inode *inode = dentry->d_inode;
@@ -1143,12 +1183,47 @@
saved_pos = *ppos;
}
+ if (ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb))) {
+ loff_t end = saved_pos + count;
+
+ /*
+ * Skip the O_DIRECT checks if we don't need
+ * them.
+ */
+ if (!direct_io || !(*direct_io))
+ break;
+
+ /*
+ * Allowing concurrent direct writes means
+ * i_size changes wouldn't be synchronized, so
+ * one node could wind up truncating another
+ * nodes writes.
+ */
+ if (end > i_size_read(inode)) {
+ *direct_io = 0;
+ break;
+ }
+
+ /*
+ * We don't fill holes during direct io, so
+ * check for them here. If any are found, the
+ * caller will have to retake some cluster
+ * locks and initiate the io as buffered.
+ */
+ ret = ocfs2_check_range_for_holes(inode, saved_pos,
+ count);
+ if (ret == 1) {
+ *direct_io = 0;
+ ret = 0;
+ } else if (ret < 0)
+ mlog_errno(ret);
+ break;
+ }
+
/*
* The rest of this loop is concerned with legacy file
* systems which don't support sparse files.
*/
- if (ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)))
- break;
newsize = count + saved_pos;
@@ -1202,55 +1277,264 @@
return ret;
}
+static inline void
+ocfs2_set_next_iovec(const struct iovec **iovp, size_t *basep, size_t bytes)
+{
+ const struct iovec *iov = *iovp;
+ size_t base = *basep;
+
+ do {
+ int copy = min(bytes, iov->iov_len - base);
+
+ bytes -= copy;
+ base += copy;
+ if (iov->iov_len == base) {
+ iov++;
+ base = 0;
+ }
+ } while (bytes);
+ *iovp = iov;
+ *basep = base;
+}
+
+static struct page * ocfs2_get_write_source(struct ocfs2_buffered_write_priv *bp,
+ const struct iovec *cur_iov,
+ size_t iov_offset)
+{
+ int ret;
+ char *buf;
+ struct page *src_page = NULL;
+
+ buf = cur_iov->iov_base + iov_offset;
+
+ if (!segment_eq(get_fs(), KERNEL_DS)) {
+ /*
+ * Pull in the user page. We want to do this outside
+ * of the meta data locks in order to preserve locking
+ * order in case of page fault.
+ */
+ ret = get_user_pages(current, current->mm,
+ (unsigned long)buf & PAGE_CACHE_MASK, 1,
+ 0, 0, &src_page, NULL);
+ if (ret == 1)
+ bp->b_src_buf = kmap(src_page);
+ else
+ src_page = ERR_PTR(-EFAULT);
+ } else {
+ bp->b_src_buf = buf;
+ }
+
+ return src_page;
+}
+
+static void ocfs2_put_write_source(struct ocfs2_buffered_write_priv *bp,
+ struct page *page)
+{
+ if (page) {
+ kunmap(page);
+ page_cache_release(page);
+ }
+}
+
+static ssize_t ocfs2_file_buffered_write(struct file *file, loff_t *ppos,
+ const struct iovec *iov,
+ unsigned long nr_segs,
+ size_t count,
+ ssize_t o_direct_written)
+{
+ int ret = 0;
+ ssize_t copied, total = 0;
+ size_t iov_offset = 0;
+ const struct iovec *cur_iov = iov;
+ struct ocfs2_buffered_write_priv bp;
+ struct page *page;
+
+ /*
+ * handle partial DIO write. Adjust cur_iov if needed.
+ */
+ ocfs2_set_next_iovec(&cur_iov, &iov_offset, o_direct_written);
+
+ do {
+ bp.b_cur_off = iov_offset;
+ bp.b_cur_iov = cur_iov;
+
+ page = ocfs2_get_write_source(&bp, cur_iov, iov_offset);
+ if (IS_ERR(page)) {
+ ret = PTR_ERR(page);
+ goto out;
+ }
+
+ copied = ocfs2_buffered_write_cluster(file, *ppos, count,
+ ocfs2_map_and_write_user_data,
+ &bp);
+
+ ocfs2_put_write_source(&bp, page);
+
+ if (copied < 0) {
+ mlog_errno(copied);
+ ret = copied;
+ goto out;
+ }
+
+ total += copied;
+ *ppos = *ppos + copied;
+ count -= copied;
+
+ ocfs2_set_next_iovec(&cur_iov, &iov_offset, copied);
+ } while(count);
+
+out:
+ return total ? total : ret;
+}
+
+static int ocfs2_check_iovec(const struct iovec *iov, size_t *counted,
+ unsigned long *nr_segs)
+{
+ size_t ocount; /* original count */
+ unsigned long seg;
+
+ ocount = 0;
+ for (seg = 0; seg < *nr_segs; seg++) {
+ const struct iovec *iv = &iov[seg];
+
+ /*
+ * If any segment has a negative length, or the cumulative
+ * length ever wraps negative then return -EINVAL.
+ */
+ ocount += iv->iov_len;
+ if (unlikely((ssize_t)(ocount|iv->iov_len) < 0))
+ return -EINVAL;
+ if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
+ continue;
+ if (seg == 0)
+ return -EFAULT;
+ *nr_segs = seg;
+ ocount -= iv->iov_len; /* This segment is no good */
+ break;
+ }
+
+ *counted = ocount;
+ return 0;
+}
+
static ssize_t ocfs2_file_aio_write(struct kiocb *iocb,
const struct iovec *iov,
unsigned long nr_segs,
loff_t pos)
{
- int ret, rw_level, have_alloc_sem = 0;
- struct file *filp = iocb->ki_filp;
- struct inode *inode = filp->f_path.dentry->d_inode;
- int appending = filp->f_flags & O_APPEND ? 1 : 0;
+ int ret, direct_io, appending, rw_level, have_alloc_sem = 0;
+ int can_do_direct, sync = 0;
+ ssize_t written = 0;
+ size_t ocount; /* original count */
+ size_t count; /* after file limit checks */
+ loff_t *ppos = &iocb->ki_pos;
+ struct file *file = iocb->ki_filp;
+ struct inode *inode = file->f_path.dentry->d_inode;
- mlog_entry("(0x%p, %u, '%.*s')\n", filp,
+ mlog_entry("(0x%p, %u, '%.*s')\n", file,
(unsigned int)nr_segs,
- filp->f_path.dentry->d_name.len,
- filp->f_path.dentry->d_name.name);
+ file->f_path.dentry->d_name.len,
+ file->f_path.dentry->d_name.name);
- /* happy write of zero bytes */
if (iocb->ki_left == 0)
return 0;
+ ret = ocfs2_check_iovec(iov, &ocount, &nr_segs);
+ if (ret)
+ return ret;
+
+ count = ocount;
+
+ vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
+
+ appending = file->f_flags & O_APPEND ? 1 : 0;
+ direct_io = file->f_flags & O_DIRECT ? 1 : 0;
+
mutex_lock(&inode->i_mutex);
+
+relock:
/* to match setattr's i_mutex -> i_alloc_sem -> rw_lock ordering */
- if (filp->f_flags & O_DIRECT) {
- have_alloc_sem = 1;
+ if (direct_io) {
down_read(&inode->i_alloc_sem);
+ have_alloc_sem = 1;
}
/* concurrent O_DIRECT writes are allowed */
- rw_level = (filp->f_flags & O_DIRECT) ? 0 : 1;
+ rw_level = !direct_io;
ret = ocfs2_rw_lock(inode, rw_level);
if (ret < 0) {
- rw_level = -1;
+ mlog_errno(ret);
+ goto out_sems;
+ }
+
+ can_do_direct = direct_io;
+ ret = ocfs2_prepare_inode_for_write(file->f_path.dentry, ppos,
+ iocb->ki_left, appending,
+ &can_do_direct);
+ if (ret < 0) {
mlog_errno(ret);
goto out;
}
- ret = ocfs2_prepare_inode_for_write(filp->f_path.dentry, &iocb->ki_pos,
- iocb->ki_left, appending);
- if (ret < 0) {
- mlog_errno(ret);
- goto out;
+ /*
+ * We can't complete the direct I/O as requested, fall back to
+ * buffered I/O.
+ */
+ if (direct_io && !can_do_direct) {
+ ocfs2_rw_unlock(inode, rw_level);
+ up_read(&inode->i_alloc_sem);
+
+ have_alloc_sem = 0;
+ rw_level = -1;
+
+ direct_io = 0;
+ sync = 1;
+ goto relock;
}
+ if (!sync && ((file->f_flags & O_SYNC) || IS_SYNC(inode)))
+ sync = 1;
+
+ /*
+ * XXX: Is it ok to execute these checks a second time?
+ */
+ ret = generic_write_checks(file, ppos, &count, S_ISBLK(inode->i_mode));
+ if (ret)
+ goto out;
+
+ /*
+ * Set pos so that sync_page_range_nolock() below understands
+ * where to start from. We might've moved it around via the
+ * calls above. The range we want to actually sync starts from
+ * *ppos here.
+ *
+ */
+ pos = *ppos;
+
/* communicate with ocfs2_dio_end_io */
ocfs2_iocb_set_rw_locked(iocb);
- ret = generic_file_aio_write_nolock(iocb, iov, nr_segs, iocb->ki_pos);
+ if (direct_io) {
+ written = generic_file_direct_write(iocb, iov, &nr_segs, *ppos,
+ ppos, count, ocount);
+ if (written < 0) {
+ ret = written;
+ goto out_dio;
+ }
+ } else {
+ written = ocfs2_file_buffered_write(file, ppos, iov, nr_segs,
+ count, written);
+ if (written < 0) {
+ ret = written;
+ if (ret != -EFAULT || ret != -ENOSPC)
+ mlog_errno(ret);
+ goto out;
+ }
+ }
+out_dio:
/* buffered aio wouldn't have proper lock coverage today */
- BUG_ON(ret == -EIOCBQUEUED && !(filp->f_flags & O_DIRECT));
+ BUG_ON(ret == -EIOCBQUEUED && !(file->f_flags & O_DIRECT));
/*
* deep in g_f_a_w_n()->ocfs2_direct_IO we pass in a ocfs2_dio_end_io
@@ -1268,14 +1552,25 @@
}
out:
+ if (rw_level != -1)
+ ocfs2_rw_unlock(inode, rw_level);
+
+out_sems:
if (have_alloc_sem)
up_read(&inode->i_alloc_sem);
- if (rw_level != -1)
- ocfs2_rw_unlock(inode, rw_level);
+
+ if (written > 0 && sync) {
+ ssize_t err;
+
+ err = sync_page_range_nolock(inode, file->f_mapping, pos, count);
+ if (err < 0)
+ written = err;
+ }
+
mutex_unlock(&inode->i_mutex);
mlog_exit(ret);
- return ret;
+ return written ? written : ret;
}
static ssize_t ocfs2_file_splice_write(struct pipe_inode_info *pipe,
@@ -1300,7 +1595,8 @@
goto out;
}
- ret = ocfs2_prepare_inode_for_write(out->f_path.dentry, ppos, len, 0);
+ ret = ocfs2_prepare_inode_for_write(out->f_path.dentry, ppos, len, 0,
+ NULL);
if (ret < 0) {
mlog_errno(ret);
goto out_unlock;