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Message-ID: <02211105388c53dc68b7f4332f9b5649d5b66b71.1755806649.git.josef@toxicpanda.com>
Date: Thu, 21 Aug 2025 16:18:13 -0400
From: Josef Bacik <josef@...icpanda.com>
To: linux-fsdevel@...r.kernel.org,
linux-btrfs@...r.kernel.org,
kernel-team@...com,
linux-ext4@...r.kernel.org,
linux-xfs@...r.kernel.org,
brauner@...nel.org,
viro@...IV.linux.org.uk
Subject: [PATCH 02/50] fs: make the i_state flags an enum
Adjusting i_state flags always means updating the values manually. Bring
these forward into the 2020's and make a nice clean macro for defining
the i_state values as an enum, providing __ variants for the cases where
we need the bit position instead of the actual value, and leaving the
actual NAME as the 1U << bit value.
Signed-off-by: Josef Bacik <josef@...icpanda.com>
---
include/linux/fs.h | 234 +++++++++++++++++++++++----------------------
1 file changed, 122 insertions(+), 112 deletions(-)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 9a1ce67eed33..e741dc453c2c 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -665,6 +665,127 @@ is_uncached_acl(struct posix_acl *acl)
#define IOP_MGTIME 0x0020
#define IOP_CACHED_LINK 0x0040
+/*
+ * Inode state bits. Protected by inode->i_lock
+ *
+ * Four bits determine the dirty state of the inode: I_DIRTY_SYNC,
+ * I_DIRTY_DATASYNC, I_DIRTY_PAGES, and I_DIRTY_TIME.
+ *
+ * Four bits define the lifetime of an inode. Initially, inodes are I_NEW,
+ * until that flag is cleared. I_WILL_FREE, I_FREEING and I_CLEAR are set at
+ * various stages of removing an inode.
+ *
+ * Two bits are used for locking and completion notification, I_NEW and I_SYNC.
+ *
+ * I_DIRTY_SYNC Inode is dirty, but doesn't have to be written on
+ * fdatasync() (unless I_DIRTY_DATASYNC is also set).
+ * Timestamp updates are the usual cause.
+ * I_DIRTY_DATASYNC Data-related inode changes pending. We keep track of
+ * these changes separately from I_DIRTY_SYNC so that we
+ * don't have to write inode on fdatasync() when only
+ * e.g. the timestamps have changed.
+ * I_DIRTY_PAGES Inode has dirty pages. Inode itself may be clean.
+ * I_DIRTY_TIME The inode itself has dirty timestamps, and the
+ * lazytime mount option is enabled. We keep track of this
+ * separately from I_DIRTY_SYNC in order to implement
+ * lazytime. This gets cleared if I_DIRTY_INODE
+ * (I_DIRTY_SYNC and/or I_DIRTY_DATASYNC) gets set. But
+ * I_DIRTY_TIME can still be set if I_DIRTY_SYNC is already
+ * in place because writeback might already be in progress
+ * and we don't want to lose the time update
+ * I_NEW Serves as both a mutex and completion notification.
+ * New inodes set I_NEW. If two processes both create
+ * the same inode, one of them will release its inode and
+ * wait for I_NEW to be released before returning.
+ * Inodes in I_WILL_FREE, I_FREEING or I_CLEAR state can
+ * also cause waiting on I_NEW, without I_NEW actually
+ * being set. find_inode() uses this to prevent returning
+ * nearly-dead inodes.
+ * I_WILL_FREE Must be set when calling write_inode_now() if i_count
+ * is zero. I_FREEING must be set when I_WILL_FREE is
+ * cleared.
+ * I_FREEING Set when inode is about to be freed but still has dirty
+ * pages or buffers attached or the inode itself is still
+ * dirty.
+ * I_CLEAR Added by clear_inode(). In this state the inode is
+ * clean and can be destroyed. Inode keeps I_FREEING.
+ *
+ * Inodes that are I_WILL_FREE, I_FREEING or I_CLEAR are
+ * prohibited for many purposes. iget() must wait for
+ * the inode to be completely released, then create it
+ * anew. Other functions will just ignore such inodes,
+ * if appropriate. I_NEW is used for waiting.
+ *
+ * I_SYNC Writeback of inode is running. The bit is set during
+ * data writeback, and cleared with a wakeup on the bit
+ * address once it is done. The bit is also used to pin
+ * the inode in memory for flusher thread.
+ *
+ * I_REFERENCED Marks the inode as recently references on the LRU list.
+ *
+ * I_WB_SWITCH Cgroup bdi_writeback switching in progress. Used to
+ * synchronize competing switching instances and to tell
+ * wb stat updates to grab the i_pages lock. See
+ * inode_switch_wbs_work_fn() for details.
+ *
+ * I_OVL_INUSE Used by overlayfs to get exclusive ownership on upper
+ * and work dirs among overlayfs mounts.
+ *
+ * I_CREATING New object's inode in the middle of setting up.
+ *
+ * I_DONTCACHE Evict inode as soon as it is not used anymore.
+ *
+ * I_SYNC_QUEUED Inode is queued in b_io or b_more_io writeback lists.
+ * Used to detect that mark_inode_dirty() should not move
+ * inode between dirty lists.
+ *
+ * I_PINNING_FSCACHE_WB Inode is pinning an fscache object for writeback.
+ *
+ * I_LRU_ISOLATING Inode is pinned being isolated from LRU without holding
+ * i_count.
+ *
+ * Q: What is the difference between I_WILL_FREE and I_FREEING?
+ *
+ * __I_{SYNC,NEW,LRU_ISOLATING} are used to derive unique addresses to wait
+ * upon. There's one free address left.
+ */
+
+/*
+ * As simple macro to define the inode state bits, __NAME will be the bit value
+ * (0, 1, 2, ...), and NAME will be the bit mask (1U << __NAME). The __NAME_SEQ
+ * is used to reset the sequence number so the next name gets the next bit value
+ * in the sequence.
+ */
+#define INODE_BIT(name) \
+ __ ## name, \
+ name = (1U << __ ## name), \
+ __ ## name ## _SEQ = __ ## name
+
+enum inode_state_bits {
+ INODE_BIT(I_NEW),
+ INODE_BIT(I_SYNC),
+ INODE_BIT(I_LRU_ISOLATING),
+ INODE_BIT(I_DIRTY_SYNC),
+ INODE_BIT(I_DIRTY_DATASYNC),
+ INODE_BIT(I_DIRTY_PAGES),
+ INODE_BIT(I_WILL_FREE),
+ INODE_BIT(I_FREEING),
+ INODE_BIT(I_CLEAR),
+ INODE_BIT(I_REFERENCED),
+ INODE_BIT(I_LINKABLE),
+ INODE_BIT(I_DIRTY_TIME),
+ INODE_BIT(I_WB_SWITCH),
+ INODE_BIT(I_OVL_INUSE),
+ INODE_BIT(I_CREATING),
+ INODE_BIT(I_DONTCACHE),
+ INODE_BIT(I_SYNC_QUEUED),
+ INODE_BIT(I_PINNING_NETFS_WB),
+};
+
+#define I_DIRTY_INODE (I_DIRTY_SYNC | I_DIRTY_DATASYNC)
+#define I_DIRTY (I_DIRTY_INODE | I_DIRTY_PAGES)
+#define I_DIRTY_ALL (I_DIRTY | I_DIRTY_TIME)
+
/*
* Keep mostly read-only and often accessed (especially for
* the RCU path lookup and 'stat' data) fields at the beginning
@@ -723,7 +844,7 @@ struct inode {
#endif
/* Misc */
- u32 i_state;
+ enum inode_state_bits i_state;
/* 32-bit hole */
struct rw_semaphore i_rwsem;
@@ -2484,117 +2605,6 @@ static inline void kiocb_clone(struct kiocb *kiocb, struct kiocb *kiocb_src,
};
}
-/*
- * Inode state bits. Protected by inode->i_lock
- *
- * Four bits determine the dirty state of the inode: I_DIRTY_SYNC,
- * I_DIRTY_DATASYNC, I_DIRTY_PAGES, and I_DIRTY_TIME.
- *
- * Four bits define the lifetime of an inode. Initially, inodes are I_NEW,
- * until that flag is cleared. I_WILL_FREE, I_FREEING and I_CLEAR are set at
- * various stages of removing an inode.
- *
- * Two bits are used for locking and completion notification, I_NEW and I_SYNC.
- *
- * I_DIRTY_SYNC Inode is dirty, but doesn't have to be written on
- * fdatasync() (unless I_DIRTY_DATASYNC is also set).
- * Timestamp updates are the usual cause.
- * I_DIRTY_DATASYNC Data-related inode changes pending. We keep track of
- * these changes separately from I_DIRTY_SYNC so that we
- * don't have to write inode on fdatasync() when only
- * e.g. the timestamps have changed.
- * I_DIRTY_PAGES Inode has dirty pages. Inode itself may be clean.
- * I_DIRTY_TIME The inode itself has dirty timestamps, and the
- * lazytime mount option is enabled. We keep track of this
- * separately from I_DIRTY_SYNC in order to implement
- * lazytime. This gets cleared if I_DIRTY_INODE
- * (I_DIRTY_SYNC and/or I_DIRTY_DATASYNC) gets set. But
- * I_DIRTY_TIME can still be set if I_DIRTY_SYNC is already
- * in place because writeback might already be in progress
- * and we don't want to lose the time update
- * I_NEW Serves as both a mutex and completion notification.
- * New inodes set I_NEW. If two processes both create
- * the same inode, one of them will release its inode and
- * wait for I_NEW to be released before returning.
- * Inodes in I_WILL_FREE, I_FREEING or I_CLEAR state can
- * also cause waiting on I_NEW, without I_NEW actually
- * being set. find_inode() uses this to prevent returning
- * nearly-dead inodes.
- * I_WILL_FREE Must be set when calling write_inode_now() if i_count
- * is zero. I_FREEING must be set when I_WILL_FREE is
- * cleared.
- * I_FREEING Set when inode is about to be freed but still has dirty
- * pages or buffers attached or the inode itself is still
- * dirty.
- * I_CLEAR Added by clear_inode(). In this state the inode is
- * clean and can be destroyed. Inode keeps I_FREEING.
- *
- * Inodes that are I_WILL_FREE, I_FREEING or I_CLEAR are
- * prohibited for many purposes. iget() must wait for
- * the inode to be completely released, then create it
- * anew. Other functions will just ignore such inodes,
- * if appropriate. I_NEW is used for waiting.
- *
- * I_SYNC Writeback of inode is running. The bit is set during
- * data writeback, and cleared with a wakeup on the bit
- * address once it is done. The bit is also used to pin
- * the inode in memory for flusher thread.
- *
- * I_REFERENCED Marks the inode as recently references on the LRU list.
- *
- * I_WB_SWITCH Cgroup bdi_writeback switching in progress. Used to
- * synchronize competing switching instances and to tell
- * wb stat updates to grab the i_pages lock. See
- * inode_switch_wbs_work_fn() for details.
- *
- * I_OVL_INUSE Used by overlayfs to get exclusive ownership on upper
- * and work dirs among overlayfs mounts.
- *
- * I_CREATING New object's inode in the middle of setting up.
- *
- * I_DONTCACHE Evict inode as soon as it is not used anymore.
- *
- * I_SYNC_QUEUED Inode is queued in b_io or b_more_io writeback lists.
- * Used to detect that mark_inode_dirty() should not move
- * inode between dirty lists.
- *
- * I_PINNING_FSCACHE_WB Inode is pinning an fscache object for writeback.
- *
- * I_LRU_ISOLATING Inode is pinned being isolated from LRU without holding
- * i_count.
- *
- * Q: What is the difference between I_WILL_FREE and I_FREEING?
- *
- * __I_{SYNC,NEW,LRU_ISOLATING} are used to derive unique addresses to wait
- * upon. There's one free address left.
- */
-#define __I_NEW 0
-#define I_NEW (1 << __I_NEW)
-#define __I_SYNC 1
-#define I_SYNC (1 << __I_SYNC)
-#define __I_LRU_ISOLATING 2
-#define I_LRU_ISOLATING (1 << __I_LRU_ISOLATING)
-
-#define I_DIRTY_SYNC (1 << 3)
-#define I_DIRTY_DATASYNC (1 << 4)
-#define I_DIRTY_PAGES (1 << 5)
-#define I_WILL_FREE (1 << 6)
-#define I_FREEING (1 << 7)
-#define I_CLEAR (1 << 8)
-#define I_REFERENCED (1 << 9)
-#define I_LINKABLE (1 << 10)
-#define I_DIRTY_TIME (1 << 11)
-#define I_WB_SWITCH (1 << 12)
-#define I_OVL_INUSE (1 << 13)
-#define I_CREATING (1 << 14)
-#define I_DONTCACHE (1 << 15)
-#define I_SYNC_QUEUED (1 << 16)
-#define I_PINNING_NETFS_WB (1 << 17)
-
-#define I_DIRTY_INODE (I_DIRTY_SYNC | I_DIRTY_DATASYNC)
-#define I_DIRTY (I_DIRTY_INODE | I_DIRTY_PAGES)
-#define I_DIRTY_ALL (I_DIRTY | I_DIRTY_TIME)
-
extern void __mark_inode_dirty(struct inode *, int);
static inline void mark_inode_dirty(struct inode *inode)
{
--
2.49.0
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