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Subject[PATCH v4 3/10] ext4: Add support FALLOC_FL_COLLAPSE_RANGE for fallocate
Date
From: Namjae Jeon <namjae.jeon@samsung.com>

Add support FALLOC_FL_COLLAPSE_RANGE for fallocate

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Ashish Sangwan <a.sangwan@samsung.com>
---
fs/ext4/ext4.h | 3 +
fs/ext4/extents.c | 297 ++++++++++++++++++++++++++++++++++++++++++-
fs/ext4/move_extent.c | 2 +-
include/trace/events/ext4.h | 25 ++++
4 files changed, 325 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index e618503..5cc015a 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2745,6 +2745,7 @@ extern int ext4_find_delalloc_cluster(struct inode *inode, ext4_lblk_t lblk);
extern int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
__u64 start, __u64 len);
extern int ext4_ext_precache(struct inode *inode);
+extern int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len);

/* move_extent.c */
extern void ext4_double_down_write_data_sem(struct inode *first,
@@ -2754,6 +2755,8 @@ extern void ext4_double_up_write_data_sem(struct inode *orig_inode,
extern int ext4_move_extents(struct file *o_filp, struct file *d_filp,
__u64 start_orig, __u64 start_donor,
__u64 len, __u64 *moved_len);
+extern int mext_next_extent(struct inode *inode, struct ext4_ext_path *path,
+ struct ext4_extent **extent);

/* page-io.c */
extern int __init ext4_init_pageio(void);
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 267c9fb..12338c1 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4566,12 +4566,16 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
unsigned int credits, blkbits = inode->i_blkbits;

/* Return error if mode is not supported */
- if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
+ if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |
+ FALLOC_FL_COLLAPSE_RANGE))
return -EOPNOTSUPP;

if (mode & FALLOC_FL_PUNCH_HOLE)
return ext4_punch_hole(inode, offset, len);

+ if (mode & FALLOC_FL_COLLAPSE_RANGE)
+ return ext4_collapse_range(inode, offset, len);
+
ret = ext4_convert_inline_data(inode);
if (ret)
return ret;
@@ -4870,3 +4874,294 @@ int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
ext4_es_lru_add(inode);
return error;
}
+
+/*
+ * ext4_access_path:
+ * Function to access the path buffer for marking it dirty.
+ * It also checks if there are sufficient credits left in the journal handle
+ * to update path.
+ */
+static int
+ext4_access_path(handle_t *handle, struct inode *inode,
+ struct ext4_ext_path *path)
+{
+ int credits, err;
+
+ /*
+ * Check if need to extend journal credits
+ * 3 for leaf, sb, and inode plus 2 (bmap and group
+ * descriptor) for each block group; assume two block
+ * groups
+ */
+ if (handle->h_buffer_credits < 7) {
+ credits = ext4_writepage_trans_blocks(inode);
+ err = ext4_ext_truncate_extend_restart(handle, inode, credits);
+ /* EAGAIN is success */
+ if (err && err != -EAGAIN)
+ return err;
+ }
+
+ err = ext4_ext_get_access(handle, inode, path);
+ return err;
+}
+
+/*
+ * ext4_ext_shift_path_extents:
+ * Shift the extents of a path structure lying between path[depth].p_ext
+ * and EXT_LAST_EXTENT(path[depth].p_hdr) downwards, by subtracting shift
+ * from starting block for each extent.
+ */
+static int
+ext4_ext_shift_path_extents(struct ext4_ext_path *path, ext4_lblk_t shift,
+ struct inode *inode, handle_t *handle,
+ ext4_lblk_t *start)
+{
+ int depth, err = 0;
+ struct ext4_extent *ex_start, *ex_last;
+ bool update = 0;
+ depth = path->p_depth;
+
+ while (depth >= 0) {
+ if (depth == path->p_depth) {
+ ex_start = path[depth].p_ext;
+ if (!ex_start)
+ return -EIO;
+
+ ex_last = EXT_LAST_EXTENT(path[depth].p_hdr);
+ if (!ex_last)
+ return -EIO;
+
+ err = ext4_access_path(handle, inode, path + depth);
+ if (err)
+ goto out;
+
+ if (ex_start == EXT_FIRST_EXTENT(path[depth].p_hdr))
+ update = 1;
+
+ *start = ex_last->ee_block +
+ ext4_ext_get_actual_len(ex_last);
+
+ while (ex_start <= ex_last) {
+ ex_start->ee_block -= shift;
+ if (ex_start >
+ EXT_FIRST_EXTENT(path[depth].p_hdr)) {
+ if (ext4_ext_try_to_merge_right(inode,
+ path, ex_start - 1))
+ ex_last--;
+ }
+ ex_start++;
+ }
+ err = ext4_ext_dirty(handle, inode, path + depth);
+ if (err)
+ goto out;
+
+ if (--depth < 0 || !update)
+ break;
+ }
+
+ /* Update index too */
+ err = ext4_access_path(handle, inode, path + depth);
+ if (err)
+ goto out;
+
+ path[depth].p_idx->ei_block -= shift;
+ err = ext4_ext_dirty(handle, inode, path + depth);
+ if (err)
+ goto out;
+
+ /* we are done if current index is not a starting index */
+ if (path[depth].p_idx != EXT_FIRST_INDEX(path[depth].p_hdr))
+ break;
+
+ depth--;
+ }
+
+out:
+ return err;
+}
+
+/*
+ * ext4_ext_shift_extents:
+ * All the extents which lies in the range from start to the last allocated
+ * block for the file are shifted downwards by shift blocks.
+ * On success, 0 is returned, error otherwise.
+ */
+static int
+ext4_ext_shift_extents(struct inode *inode, handle_t *handle,
+ ext4_lblk_t start, ext4_lblk_t shift)
+{
+ struct ext4_ext_path *path;
+ int ret = 0, depth;
+ struct ext4_extent *extent;
+ ext4_lblk_t stop_block, current_block;
+ ext4_lblk_t ex_start, ex_end;
+
+ /* Let path point to the last extent */
+ path = ext4_ext_find_extent(inode, EXT_MAX_BLOCKS - 1, NULL, 0);
+ if (IS_ERR(path))
+ return PTR_ERR(path);
+
+ depth = path->p_depth;
+ extent = path[depth].p_ext;
+ if (!extent) {
+ ext4_ext_drop_refs(path);
+ kfree(path);
+ return ret;
+ }
+
+ stop_block = extent->ee_block + ext4_ext_get_actual_len(extent);
+ ext4_ext_drop_refs(path);
+ kfree(path);
+
+ /* Nothing to shift, if hole is at the end of file */
+ if (start >= stop_block)
+ return ret;
+
+ /*
+ * Don't start shifting extents until we make sure the hole is big
+ * enough to accomodate the shift.
+ */
+ path = ext4_ext_find_extent(inode, start - 1, NULL, 0);
+ depth = path->p_depth;
+ extent = path[depth].p_ext;
+ ex_start = extent->ee_block;
+ ex_end = extent->ee_block + ext4_ext_get_actual_len(extent);
+ ext4_ext_drop_refs(path);
+ kfree(path);
+
+ if ((ex_start > start - 1 && shift > ex_start) ||
+ (ex_end > start - shift))
+ return -EINVAL;
+
+ /* Its safe to start updating extents */
+ while (start < stop_block) {
+ path = ext4_ext_find_extent(inode, start, NULL, 0);
+ if (IS_ERR(path))
+ return PTR_ERR(path);
+ depth = path->p_depth;
+ extent = path[depth].p_ext;
+ current_block = extent->ee_block;
+ if (start > current_block) {
+ /* Hole, move to the next extent */
+ ret = mext_next_extent(inode, path, &extent);
+ if (ret != 0) {
+ ext4_ext_drop_refs(path);
+ kfree(path);
+ if (ret == 1)
+ ret = 0;
+ break;
+ }
+ }
+ ret = ext4_ext_shift_path_extents(path, shift, inode,
+ handle, &start);
+ ext4_ext_drop_refs(path);
+ kfree(path);
+ if (ret)
+ break;
+ }
+
+ return ret;
+}
+
+/*
+ * ext4_collapse_range:
+ * This implements the fallocate's collapse range functionality for ext4
+ * Returns: 0 and non-zero on error.
+ */
+int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len)
+{
+ struct super_block *sb = inode->i_sb;
+ ext4_lblk_t punch_start, punch_stop;
+ handle_t *handle;
+ unsigned int credits;
+ unsigned int rounding;
+ loff_t ioffset, new_size;
+ int ret;
+ unsigned blksize_mask = (1 << inode->i_blkbits) - 1;
+
+ BUG_ON(offset + len > i_size_read(inode));
+
+ /* Collapse range works only on fs block size aligned offsets. */
+ if (offset & blksize_mask || len & blksize_mask)
+ return -EINVAL;
+
+ if (!S_ISREG(inode->i_mode))
+ return -EOPNOTSUPP;
+
+ if (EXT4_SB(sb)->s_cluster_ratio > 1)
+ return -EOPNOTSUPP;
+
+ /* Currently just for extent based files */
+ if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
+ return -EOPNOTSUPP;
+
+ if (IS_SWAPFILE(inode))
+ return -ETXTBSY;
+
+ trace_ext4_collapse_range(inode, offset, len);
+
+ punch_start = offset >> EXT4_BLOCK_SIZE_BITS(sb);
+ punch_stop = (offset + len) >> EXT4_BLOCK_SIZE_BITS(sb);
+
+ rounding = max_t(uint, 1 << EXT4_BLOCK_SIZE_BITS(sb), PAGE_CACHE_SIZE);
+ ioffset = offset & ~(rounding - 1);
+
+ /* Write out all dirty pages */
+ ret = filemap_write_and_wait_range(inode->i_mapping, ioffset, -1);
+ if (ret)
+ return ret;
+
+ /* Take mutex lock */
+ mutex_lock(&inode->i_mutex);
+
+ /* Wait for existing dio to complete */
+ ext4_inode_block_unlocked_dio(inode);
+ inode_dio_wait(inode);
+
+ truncate_pagecache_range(inode, ioffset, -1);
+
+ credits = ext4_writepage_trans_blocks(inode);
+ handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, credits);
+ if (IS_ERR(handle)) {
+ ret = PTR_ERR(handle);
+ goto out_dio;
+ }
+
+ down_write(&EXT4_I(inode)->i_data_sem);
+
+ ext4_discard_preallocations(inode);
+
+ ret = ext4_es_remove_extent(inode, punch_start,
+ EXT_MAX_BLOCKS - punch_start - 1);
+ if (ret)
+ goto journal_stop;
+
+ ret = ext4_ext_remove_space(inode, punch_start, punch_stop - 1);
+ if (ret)
+ goto journal_stop;
+
+ ret = ext4_ext_shift_extents(inode, handle, punch_stop,
+ punch_stop - punch_start);
+ if (ret)
+ goto journal_stop;
+
+ if ((offset + len) > i_size_read(inode))
+ new_size = offset;
+ else
+ new_size = i_size_read(inode) - len;
+
+ truncate_setsize(inode, new_size);
+ EXT4_I(inode)->i_disksize = new_size;
+
+ inode->i_mtime = inode->i_ctime = ext4_current_time(inode);
+ ext4_mark_inode_dirty(handle, inode);
+
+journal_stop:
+ ext4_journal_stop(handle);
+ up_write(&EXT4_I(inode)->i_data_sem);
+
+out_dio:
+ ext4_inode_resume_unlocked_dio(inode);
+ mutex_unlock(&inode->i_mutex);
+ return ret;
+}
diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index 773b503..b474558 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -76,7 +76,7 @@ copy_extent_status(struct ext4_extent *src, struct ext4_extent *dest)
* ext4_ext_path structure refers to the last extent, or a negative error
* value on failure.
*/
-static int
+int
mext_next_extent(struct inode *inode, struct ext4_ext_path *path,
struct ext4_extent **extent)
{
diff --git a/include/trace/events/ext4.h b/include/trace/events/ext4.h
index 197d312..90e2f71 100644
--- a/include/trace/events/ext4.h
+++ b/include/trace/events/ext4.h
@@ -2410,6 +2410,31 @@ TRACE_EVENT(ext4_es_shrink_exit,
__entry->shrunk_nr, __entry->cache_cnt)
);

+TRACE_EVENT(ext4_collapse_range,
+ TP_PROTO(struct inode *inode, loff_t offset, loff_t len),
+
+ TP_ARGS(inode, offset, len),
+
+ TP_STRUCT__entry(
+ __field(dev_t, dev)
+ __field(ino_t, ino)
+ __field(loff_t, offset)
+ __field(loff_t, len)
+ ),
+
+ TP_fast_assign(
+ __entry->dev = inode->i_sb->s_dev;
+ __entry->ino = inode->i_ino;
+ __entry->offset = offset;
+ __entry->len = len;
+ ),
+
+ TP_printk("dev %d,%d ino %lu offset %lld len %lld",
+ MAJOR(__entry->dev), MINOR(__entry->dev),
+ (unsigned long) __entry->ino,
+ __entry->offset, __entry->len)
+);
+
#endif /* _TRACE_EXT4_H */

/* This part must be outside protection */
--
1.7.9.5


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