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-rw-r--r--fs/ubifs/budget.c38
-rw-r--r--fs/ubifs/super.c10
-rw-r--r--fs/ubifs/ubifs.h2
3 files changed, 40 insertions, 10 deletions
diff --git a/fs/ubifs/budget.c b/fs/ubifs/budget.c
index 7851480..101d278 100644
--- a/fs/ubifs/budget.c
+++ b/fs/ubifs/budget.c
@@ -747,14 +747,24 @@ long long ubifs_reported_space(const struct ubifs_info *c, uint64_t free)
}
/**
- * ubifs_budg_get_free_space - return amount of free space.
+ * ubifs_get_free_space - return amount of free space.
* @c: UBIFS file-system description object
*
- * This function returns amount of free space on the file-system.
+ * This function calculates amount of free space to report to user-space.
+ *
+ * Because UBIFS may introduce substantial overhead (the index, node headers,
+ * alighment, wastage at the end of eraseblocks, etc), it cannot report real
+ * amount of free flash space it has (well, because not all dirty space is
+ * reclamable, UBIFS does not actually know the real amount). If UBIFS did so,
+ * it would bread user expectetion about what free space is. Users seem to
+ * accustomed to assume that if the file-system reports N bytes of free space,
+ * they would be able to fit a file of N bytes to the FS. This almost works for
+ * traditional file-systems, because they have way less overhead than UBIFS.
+ * So, to keep users happy, UBIFS tries to take the overhead into account.
*/
-long long ubifs_budg_get_free_space(struct ubifs_info *c)
+long long ubifs_get_free_space(struct ubifs_info *c)
{
- int min_idx_lebs;
+ int min_idx_lebs, rsvd_idx_lebs, lebs;
long long available, outstanding, free;
spin_lock(&c->space_lock);
@@ -771,6 +781,26 @@ long long ubifs_budg_get_free_space(struct ubifs_info *c)
}
available = ubifs_calc_available(c, min_idx_lebs);
+
+ /*
+ * When reporting free space to user-space, UBIFS guarantees that it is
+ * possible to write a file of free space size. This means that for
+ * empty LEBs we may use more precise calculations than
+ * 'ubifs_calc_available()' is using. Namely, we know that in empty
+ * LEBs we would waste only @c->leb_overhead bytes, not @c->dark_wm.
+ * Thus, amend the available space.
+ *
+ * Note, the calculations below are similar to what we have in
+ * 'do_budget_space()', so refer there for comments.
+ */
+ if (min_idx_lebs > c->lst.idx_lebs)
+ rsvd_idx_lebs = min_idx_lebs - c->lst.idx_lebs;
+ else
+ rsvd_idx_lebs = 0;
+ lebs = c->lst.empty_lebs + c->freeable_cnt + c->idx_gc_cnt -
+ c->lst.taken_empty_lebs;
+ lebs -= rsvd_idx_lebs;
+ available += lebs * (c->dark_wm - c->leb_overhead);
spin_unlock(&c->space_lock);
if (available > outstanding)
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index be23fd3..1207bd5 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -371,7 +371,7 @@ static int ubifs_statfs(struct dentry *dentry, struct kstatfs *buf)
struct ubifs_info *c = dentry->d_sb->s_fs_info;
unsigned long long free;
- free = ubifs_budg_get_free_space(c);
+ free = ubifs_get_free_space(c);
dbg_gen("free space %lld bytes (%lld blocks)",
free, free >> UBIFS_BLOCK_SHIFT);
@@ -653,11 +653,11 @@ static int init_constants_late(struct ubifs_info *c)
* internally because it does not make much sense for UBIFS, but it is
* necessary to report something for the 'statfs()' call.
*
- * Subtract the LEB reserved for GC and the LEB which is reserved for
- * deletions.
+ * Subtract the LEB reserved for GC, the LEB which is reserved for
+ * deletions, and assume only one journal head is available.
*/
- tmp64 = c->main_lebs - 2;
- tmp64 *= (uint64_t)c->leb_size - c->dark_wm;
+ tmp64 = c->main_lebs - 2 - c->jhead_cnt + 1;
+ tmp64 *= (uint64_t)c->leb_size - c->leb_overhead;
tmp64 = ubifs_reported_space(c, tmp64);
c->block_cnt = tmp64 >> UBIFS_BLOCK_SHIFT;
diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index 57e5854..17c620b 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -1443,7 +1443,7 @@ void ubifs_release_ino_dirty(struct ubifs_info *c, struct inode *inode,
struct ubifs_budget_req *req);
void ubifs_cancel_ino_op(struct ubifs_info *c, struct inode *inode,
struct ubifs_budget_req *req);
-long long ubifs_budg_get_free_space(struct ubifs_info *c);
+long long ubifs_get_free_space(struct ubifs_info *c);
int ubifs_calc_min_idx_lebs(struct ubifs_info *c);
void ubifs_convert_page_budget(struct ubifs_info *c);
long long ubifs_reported_space(const struct ubifs_info *c, uint64_t free);