Move xfs_iunlink and xfs_iunlink_remove to libxfs.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
#include "xfs_ialloc.h"
#include "xfs_health.h"
#include "xfs_bmap.h"
+#include "xfs_error.h"
+#include "xfs_trace.h"
+#include "xfs_ag.h"
+#include "xfs_iunlink_item.h"
uint16_t
xfs_flags2diflags(
xfs_trans_log_inode(tp, ip, flags);
}
+
+/*
+ * In-Core Unlinked List Lookups
+ * =============================
+ *
+ * Every inode is supposed to be reachable from some other piece of metadata
+ * with the exception of the root directory. Inodes with a connection to a
+ * file descriptor but not linked from anywhere in the on-disk directory tree
+ * are collectively known as unlinked inodes, though the filesystem itself
+ * maintains links to these inodes so that on-disk metadata are consistent.
+ *
+ * XFS implements a per-AG on-disk hash table of unlinked inodes. The AGI
+ * header contains a number of buckets that point to an inode, and each inode
+ * record has a pointer to the next inode in the hash chain. This
+ * singly-linked list causes scaling problems in the iunlink remove function
+ * because we must walk that list to find the inode that points to the inode
+ * being removed from the unlinked hash bucket list.
+ *
+ * Hence we keep an in-memory double linked list to link each inode on an
+ * unlinked list. Because there are 64 unlinked lists per AGI, keeping pointer
+ * based lists would require having 64 list heads in the perag, one for each
+ * list. This is expensive in terms of memory (think millions of AGs) and cache
+ * misses on lookups. Instead, use the fact that inodes on the unlinked list
+ * must be referenced at the VFS level to keep them on the list and hence we
+ * have an existence guarantee for inodes on the unlinked list.
+ *
+ * Given we have an existence guarantee, we can use lockless inode cache lookups
+ * to resolve aginos to xfs inodes. This means we only need 8 bytes per inode
+ * for the double linked unlinked list, and we don't need any extra locking to
+ * keep the list safe as all manipulations are done under the AGI buffer lock.
+ * Keeping the list up to date does not require memory allocation, just finding
+ * the XFS inode and updating the next/prev unlinked list aginos.
+ */
+
+/*
+ * Update the prev pointer of the next agino. Returns -ENOLINK if the inode
+ * is not in cache.
+ */
+static int
+xfs_iunlink_update_backref(
+ struct xfs_perag *pag,
+ xfs_agino_t prev_agino,
+ xfs_agino_t next_agino)
+{
+ struct xfs_inode *ip;
+
+ /* No update necessary if we are at the end of the list. */
+ if (next_agino == NULLAGINO)
+ return 0;
+
+ ip = xfs_iunlink_lookup(pag, next_agino);
+ if (!ip)
+ return -ENOLINK;
+
+ ip->i_prev_unlinked = prev_agino;
+ return 0;
+}
+
+/*
+ * Point the AGI unlinked bucket at an inode and log the results. The caller
+ * is responsible for validating the old value.
+ */
+STATIC int
+xfs_iunlink_update_bucket(
+ struct xfs_trans *tp,
+ struct xfs_perag *pag,
+ struct xfs_buf *agibp,
+ unsigned int bucket_index,
+ xfs_agino_t new_agino)
+{
+ struct xfs_agi *agi = agibp->b_addr;
+ xfs_agino_t old_value;
+ int offset;
+
+ ASSERT(xfs_verify_agino_or_null(pag, new_agino));
+
+ old_value = be32_to_cpu(agi->agi_unlinked[bucket_index]);
+ trace_xfs_iunlink_update_bucket(tp->t_mountp, pag->pag_agno, bucket_index,
+ old_value, new_agino);
+
+ /*
+ * We should never find the head of the list already set to the value
+ * passed in because either we're adding or removing ourselves from the
+ * head of the list.
+ */
+ if (old_value == new_agino) {
+ xfs_buf_mark_corrupt(agibp);
+ xfs_ag_mark_sick(pag, XFS_SICK_AG_AGI);
+ return -EFSCORRUPTED;
+ }
+
+ agi->agi_unlinked[bucket_index] = cpu_to_be32(new_agino);
+ offset = offsetof(struct xfs_agi, agi_unlinked) +
+ (sizeof(xfs_agino_t) * bucket_index);
+ xfs_trans_log_buf(tp, agibp, offset, offset + sizeof(xfs_agino_t) - 1);
+ return 0;
+}
+
+static int
+xfs_iunlink_insert_inode(
+ struct xfs_trans *tp,
+ struct xfs_perag *pag,
+ struct xfs_buf *agibp,
+ struct xfs_inode *ip)
+{
+ struct xfs_mount *mp = tp->t_mountp;
+ struct xfs_agi *agi = agibp->b_addr;
+ xfs_agino_t next_agino;
+ xfs_agino_t agino = XFS_INO_TO_AGINO(mp, ip->i_ino);
+ short bucket_index = agino % XFS_AGI_UNLINKED_BUCKETS;
+ int error;
+
+ /*
+ * Get the index into the agi hash table for the list this inode will
+ * go on. Make sure the pointer isn't garbage and that this inode
+ * isn't already on the list.
+ */
+ next_agino = be32_to_cpu(agi->agi_unlinked[bucket_index]);
+ if (next_agino == agino ||
+ !xfs_verify_agino_or_null(pag, next_agino)) {
+ xfs_buf_mark_corrupt(agibp);
+ xfs_ag_mark_sick(pag, XFS_SICK_AG_AGI);
+ return -EFSCORRUPTED;
+ }
+
+ /*
+ * Update the prev pointer in the next inode to point back to this
+ * inode.
+ */
+ error = xfs_iunlink_update_backref(pag, agino, next_agino);
+ if (error == -ENOLINK)
+ error = xfs_iunlink_reload_next(tp, agibp, agino, next_agino);
+ if (error)
+ return error;
+
+ if (next_agino != NULLAGINO) {
+ /*
+ * There is already another inode in the bucket, so point this
+ * inode to the current head of the list.
+ */
+ error = xfs_iunlink_log_inode(tp, ip, pag, next_agino);
+ if (error)
+ return error;
+ ip->i_next_unlinked = next_agino;
+ }
+
+ /* Point the head of the list to point to this inode. */
+ ip->i_prev_unlinked = NULLAGINO;
+ return xfs_iunlink_update_bucket(tp, pag, agibp, bucket_index, agino);
+}
+
+/*
+ * This is called when the inode's link count has gone to 0 or we are creating
+ * a tmpfile via O_TMPFILE. The inode @ip must have nlink == 0.
+ *
+ * We place the on-disk inode on a list in the AGI. It will be pulled from this
+ * list when the inode is freed.
+ */
+int
+xfs_iunlink(
+ struct xfs_trans *tp,
+ struct xfs_inode *ip)
+{
+ struct xfs_mount *mp = tp->t_mountp;
+ struct xfs_perag *pag;
+ struct xfs_buf *agibp;
+ int error;
+
+ ASSERT(VFS_I(ip)->i_nlink == 0);
+ ASSERT(VFS_I(ip)->i_mode != 0);
+ trace_xfs_iunlink(ip);
+
+ pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
+
+ /* Get the agi buffer first. It ensures lock ordering on the list. */
+ error = xfs_read_agi(pag, tp, 0, &agibp);
+ if (error)
+ goto out;
+
+ error = xfs_iunlink_insert_inode(tp, pag, agibp, ip);
+out:
+ xfs_perag_put(pag);
+ return error;
+}
+
+static int
+xfs_iunlink_remove_inode(
+ struct xfs_trans *tp,
+ struct xfs_perag *pag,
+ struct xfs_buf *agibp,
+ struct xfs_inode *ip)
+{
+ struct xfs_mount *mp = tp->t_mountp;
+ struct xfs_agi *agi = agibp->b_addr;
+ xfs_agino_t agino = XFS_INO_TO_AGINO(mp, ip->i_ino);
+ xfs_agino_t head_agino;
+ short bucket_index = agino % XFS_AGI_UNLINKED_BUCKETS;
+ int error;
+
+ trace_xfs_iunlink_remove(ip);
+
+ /*
+ * Get the index into the agi hash table for the list this inode will
+ * go on. Make sure the head pointer isn't garbage.
+ */
+ head_agino = be32_to_cpu(agi->agi_unlinked[bucket_index]);
+ if (!xfs_verify_agino(pag, head_agino)) {
+ XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp,
+ agi, sizeof(*agi));
+ xfs_ag_mark_sick(pag, XFS_SICK_AG_AGI);
+ return -EFSCORRUPTED;
+ }
+
+ /*
+ * Set our inode's next_unlinked pointer to NULL and then return
+ * the old pointer value so that we can update whatever was previous
+ * to us in the list to point to whatever was next in the list.
+ */
+ error = xfs_iunlink_log_inode(tp, ip, pag, NULLAGINO);
+ if (error)
+ return error;
+
+ /*
+ * Update the prev pointer in the next inode to point back to previous
+ * inode in the chain.
+ */
+ error = xfs_iunlink_update_backref(pag, ip->i_prev_unlinked,
+ ip->i_next_unlinked);
+ if (error == -ENOLINK)
+ error = xfs_iunlink_reload_next(tp, agibp, ip->i_prev_unlinked,
+ ip->i_next_unlinked);
+ if (error)
+ return error;
+
+ if (head_agino != agino) {
+ struct xfs_inode *prev_ip;
+
+ prev_ip = xfs_iunlink_lookup(pag, ip->i_prev_unlinked);
+ if (!prev_ip) {
+ xfs_inode_mark_sick(ip, XFS_SICK_INO_CORE);
+ return -EFSCORRUPTED;
+ }
+
+ error = xfs_iunlink_log_inode(tp, prev_ip, pag,
+ ip->i_next_unlinked);
+ prev_ip->i_next_unlinked = ip->i_next_unlinked;
+ } else {
+ /* Point the head of the list to the next unlinked inode. */
+ error = xfs_iunlink_update_bucket(tp, pag, agibp, bucket_index,
+ ip->i_next_unlinked);
+ }
+
+ ip->i_next_unlinked = NULLAGINO;
+ ip->i_prev_unlinked = 0;
+ return error;
+}
+
+/*
+ * Pull the on-disk inode from the AGI unlinked list.
+ */
+int
+xfs_iunlink_remove(
+ struct xfs_trans *tp,
+ struct xfs_perag *pag,
+ struct xfs_inode *ip)
+{
+ struct xfs_buf *agibp;
+ int error;
+
+ trace_xfs_iunlink_remove(ip);
+
+ /* Get the agi buffer first. It ensures lock ordering on the list. */
+ error = xfs_read_agi(pag, tp, 0, &agibp);
+ if (error)
+ return error;
+
+ return xfs_iunlink_remove_inode(tp, pag, agibp, ip);
+}
void xfs_inode_init(struct xfs_trans *tp, const struct xfs_icreate_args *args,
struct xfs_inode *ip);
+int xfs_iunlink(struct xfs_trans *tp, struct xfs_inode *ip);
+int xfs_iunlink_remove(struct xfs_trans *tp, struct xfs_perag *pag,
+ struct xfs_inode *ip);
+
#endif /* __XFS_INODE_UTIL_H__ */
return error;
}
-/*
- * In-Core Unlinked List Lookups
- * =============================
- *
- * Every inode is supposed to be reachable from some other piece of metadata
- * with the exception of the root directory. Inodes with a connection to a
- * file descriptor but not linked from anywhere in the on-disk directory tree
- * are collectively known as unlinked inodes, though the filesystem itself
- * maintains links to these inodes so that on-disk metadata are consistent.
- *
- * XFS implements a per-AG on-disk hash table of unlinked inodes. The AGI
- * header contains a number of buckets that point to an inode, and each inode
- * record has a pointer to the next inode in the hash chain. This
- * singly-linked list causes scaling problems in the iunlink remove function
- * because we must walk that list to find the inode that points to the inode
- * being removed from the unlinked hash bucket list.
- *
- * Hence we keep an in-memory double linked list to link each inode on an
- * unlinked list. Because there are 64 unlinked lists per AGI, keeping pointer
- * based lists would require having 64 list heads in the perag, one for each
- * list. This is expensive in terms of memory (think millions of AGs) and cache
- * misses on lookups. Instead, use the fact that inodes on the unlinked list
- * must be referenced at the VFS level to keep them on the list and hence we
- * have an existence guarantee for inodes on the unlinked list.
- *
- * Given we have an existence guarantee, we can use lockless inode cache lookups
- * to resolve aginos to xfs inodes. This means we only need 8 bytes per inode
- * for the double linked unlinked list, and we don't need any extra locking to
- * keep the list safe as all manipulations are done under the AGI buffer lock.
- * Keeping the list up to date does not require memory allocation, just finding
- * the XFS inode and updating the next/prev unlinked list aginos.
- */
-
/*
* Find an inode on the unlinked list. This does not take references to the
* inode as we have existence guarantees by holding the AGI buffer lock and that
return ip;
}
-/*
- * Update the prev pointer of the next agino. Returns -ENOLINK if the inode
- * is not in cache.
- */
-static int
-xfs_iunlink_update_backref(
- struct xfs_perag *pag,
- xfs_agino_t prev_agino,
- xfs_agino_t next_agino)
-{
- struct xfs_inode *ip;
-
- /* No update necessary if we are at the end of the list. */
- if (next_agino == NULLAGINO)
- return 0;
-
- ip = xfs_iunlink_lookup(pag, next_agino);
- if (!ip)
- return -ENOLINK;
-
- ip->i_prev_unlinked = prev_agino;
- return 0;
-}
-
-/*
- * Point the AGI unlinked bucket at an inode and log the results. The caller
- * is responsible for validating the old value.
- */
-STATIC int
-xfs_iunlink_update_bucket(
- struct xfs_trans *tp,
- struct xfs_perag *pag,
- struct xfs_buf *agibp,
- unsigned int bucket_index,
- xfs_agino_t new_agino)
-{
- struct xfs_agi *agi = agibp->b_addr;
- xfs_agino_t old_value;
- int offset;
-
- ASSERT(xfs_verify_agino_or_null(pag, new_agino));
-
- old_value = be32_to_cpu(agi->agi_unlinked[bucket_index]);
- trace_xfs_iunlink_update_bucket(tp->t_mountp, pag->pag_agno, bucket_index,
- old_value, new_agino);
-
- /*
- * We should never find the head of the list already set to the value
- * passed in because either we're adding or removing ourselves from the
- * head of the list.
- */
- if (old_value == new_agino) {
- xfs_buf_mark_corrupt(agibp);
- xfs_ag_mark_sick(pag, XFS_SICK_AG_AGI);
- return -EFSCORRUPTED;
- }
-
- agi->agi_unlinked[bucket_index] = cpu_to_be32(new_agino);
- offset = offsetof(struct xfs_agi, agi_unlinked) +
- (sizeof(xfs_agino_t) * bucket_index);
- xfs_trans_log_buf(tp, agibp, offset, offset + sizeof(xfs_agino_t) - 1);
- return 0;
-}
-
/*
* Load the inode @next_agino into the cache and set its prev_unlinked pointer
* to @prev_agino. Caller must hold the AGI to synchronize with other changes
* to the unlinked list.
*/
-STATIC int
+int
xfs_iunlink_reload_next(
struct xfs_trans *tp,
struct xfs_buf *agibp,
return error;
}
-static int
-xfs_iunlink_insert_inode(
- struct xfs_trans *tp,
- struct xfs_perag *pag,
- struct xfs_buf *agibp,
- struct xfs_inode *ip)
-{
- struct xfs_mount *mp = tp->t_mountp;
- struct xfs_agi *agi = agibp->b_addr;
- xfs_agino_t next_agino;
- xfs_agino_t agino = XFS_INO_TO_AGINO(mp, ip->i_ino);
- short bucket_index = agino % XFS_AGI_UNLINKED_BUCKETS;
- int error;
-
- /*
- * Get the index into the agi hash table for the list this inode will
- * go on. Make sure the pointer isn't garbage and that this inode
- * isn't already on the list.
- */
- next_agino = be32_to_cpu(agi->agi_unlinked[bucket_index]);
- if (next_agino == agino ||
- !xfs_verify_agino_or_null(pag, next_agino)) {
- xfs_buf_mark_corrupt(agibp);
- xfs_ag_mark_sick(pag, XFS_SICK_AG_AGI);
- return -EFSCORRUPTED;
- }
-
- /*
- * Update the prev pointer in the next inode to point back to this
- * inode.
- */
- error = xfs_iunlink_update_backref(pag, agino, next_agino);
- if (error == -ENOLINK)
- error = xfs_iunlink_reload_next(tp, agibp, agino, next_agino);
- if (error)
- return error;
-
- if (next_agino != NULLAGINO) {
- /*
- * There is already another inode in the bucket, so point this
- * inode to the current head of the list.
- */
- error = xfs_iunlink_log_inode(tp, ip, pag, next_agino);
- if (error)
- return error;
- ip->i_next_unlinked = next_agino;
- }
-
- /* Point the head of the list to point to this inode. */
- ip->i_prev_unlinked = NULLAGINO;
- return xfs_iunlink_update_bucket(tp, pag, agibp, bucket_index, agino);
-}
-
-/*
- * This is called when the inode's link count has gone to 0 or we are creating
- * a tmpfile via O_TMPFILE. The inode @ip must have nlink == 0.
- *
- * We place the on-disk inode on a list in the AGI. It will be pulled from this
- * list when the inode is freed.
- */
-int
-xfs_iunlink(
- struct xfs_trans *tp,
- struct xfs_inode *ip)
-{
- struct xfs_mount *mp = tp->t_mountp;
- struct xfs_perag *pag;
- struct xfs_buf *agibp;
- int error;
-
- ASSERT(VFS_I(ip)->i_nlink == 0);
- ASSERT(VFS_I(ip)->i_mode != 0);
- trace_xfs_iunlink(ip);
-
- pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
-
- /* Get the agi buffer first. It ensures lock ordering on the list. */
- error = xfs_read_agi(pag, tp, 0, &agibp);
- if (error)
- goto out;
-
- error = xfs_iunlink_insert_inode(tp, pag, agibp, ip);
-out:
- xfs_perag_put(pag);
- return error;
-}
-
-static int
-xfs_iunlink_remove_inode(
- struct xfs_trans *tp,
- struct xfs_perag *pag,
- struct xfs_buf *agibp,
- struct xfs_inode *ip)
-{
- struct xfs_mount *mp = tp->t_mountp;
- struct xfs_agi *agi = agibp->b_addr;
- xfs_agino_t agino = XFS_INO_TO_AGINO(mp, ip->i_ino);
- xfs_agino_t head_agino;
- short bucket_index = agino % XFS_AGI_UNLINKED_BUCKETS;
- int error;
-
- trace_xfs_iunlink_remove(ip);
-
- /*
- * Get the index into the agi hash table for the list this inode will
- * go on. Make sure the head pointer isn't garbage.
- */
- head_agino = be32_to_cpu(agi->agi_unlinked[bucket_index]);
- if (!xfs_verify_agino(pag, head_agino)) {
- XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp,
- agi, sizeof(*agi));
- xfs_ag_mark_sick(pag, XFS_SICK_AG_AGI);
- return -EFSCORRUPTED;
- }
-
- /*
- * Set our inode's next_unlinked pointer to NULL and then return
- * the old pointer value so that we can update whatever was previous
- * to us in the list to point to whatever was next in the list.
- */
- error = xfs_iunlink_log_inode(tp, ip, pag, NULLAGINO);
- if (error)
- return error;
-
- /*
- * Update the prev pointer in the next inode to point back to previous
- * inode in the chain.
- */
- error = xfs_iunlink_update_backref(pag, ip->i_prev_unlinked,
- ip->i_next_unlinked);
- if (error == -ENOLINK)
- error = xfs_iunlink_reload_next(tp, agibp, ip->i_prev_unlinked,
- ip->i_next_unlinked);
- if (error)
- return error;
-
- if (head_agino != agino) {
- struct xfs_inode *prev_ip;
-
- prev_ip = xfs_iunlink_lookup(pag, ip->i_prev_unlinked);
- if (!prev_ip) {
- xfs_inode_mark_sick(ip, XFS_SICK_INO_CORE);
- return -EFSCORRUPTED;
- }
-
- error = xfs_iunlink_log_inode(tp, prev_ip, pag,
- ip->i_next_unlinked);
- prev_ip->i_next_unlinked = ip->i_next_unlinked;
- } else {
- /* Point the head of the list to the next unlinked inode. */
- error = xfs_iunlink_update_bucket(tp, pag, agibp, bucket_index,
- ip->i_next_unlinked);
- }
-
- ip->i_next_unlinked = NULLAGINO;
- ip->i_prev_unlinked = 0;
- return error;
-}
-
-/*
- * Pull the on-disk inode from the AGI unlinked list.
- */
-int
-xfs_iunlink_remove(
- struct xfs_trans *tp,
- struct xfs_perag *pag,
- struct xfs_inode *ip)
-{
- struct xfs_buf *agibp;
- int error;
-
- trace_xfs_iunlink_remove(ip);
-
- /* Get the agi buffer first. It ensures lock ordering on the list. */
- error = xfs_read_agi(pag, tp, 0, &agibp);
- if (error)
- return error;
-
- return xfs_iunlink_remove_inode(tp, pag, agibp, ip);
-}
-
/*
* Look up the inode number specified and if it is not already marked XFS_ISTALE
* mark it stale. We should only find clean inodes in this lookup that aren't
bool xfs_inode_needs_inactive(struct xfs_inode *ip);
-int xfs_iunlink(struct xfs_trans *tp, struct xfs_inode *ip);
-int xfs_iunlink_remove(struct xfs_trans *tp, struct xfs_perag *pag,
- struct xfs_inode *ip);
struct xfs_inode *xfs_iunlink_lookup(struct xfs_perag *pag, xfs_agino_t agino);
+int xfs_iunlink_reload_next(struct xfs_trans *tp, struct xfs_buf *agibp,
+ xfs_agino_t prev_agino, xfs_agino_t next_agino);
void xfs_end_io(struct work_struct *work);
projects / thirdparty / kernel / linux.git / commitdiff
